Filed Pursuant to Rule 424(b)(4)
                                           Registration Number 333-102843
                                           and Registration Number 333-104399





PROSPECTUS

                              1,800,000 SHARES


                          [Allegiant Bancorp logo]


                                COMMON STOCK


         We are selling 1,800,000 shares of our common stock. Our common
stock is listed on the Nasdaq National Market under the symbol "ALLE." On
April 8, 2003, the last sale price of our common stock as reported by
the Nasdaq National Market was $17.07 per share.


         INVESTING IN OUR COMMON STOCK INVOLVES SIGNIFICANT RISKS. YOU
SHOULD READ THE "RISK FACTORS" SECTION BEGINNING ON PAGE 8 BEFORE INVESTING.

         NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE
SECURITIES COMMISSION OR REGULATORY BODY HAS APPROVED OR DISAPPROVED OF
THESE SECURITIES OR DETERMINED IF THIS PROSPECTUS IS TRUTHFUL OR COMPLETE.
ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.

         THESE SECURITIES ARE NOT DEPOSITS OR ACCOUNTS OR OBLIGATIONS OF ANY
BANK AND ARE NOT INSURED BY THE FEDERAL DEPOSIT INSURANCE CORPORATION OR ANY
OTHER GOVERNMENTAL AGENCY.




                                                     PER SHARE       TOTAL
                                                    -----------    ---------

                                                            
Public offering price............................      $16.50     $29,700,000

Underwriting discount............................      $ 0.94     $ 1,692,000

Proceeds, before expenses, to Allegiant..........      $15.56     $28,008,000



         This is a firm commitment offering. We have granted to the
underwriters a 30-day option to purchase up to 270,000 additional shares to
cover over-allotments, if any.


         The underwriters expect to deliver the shares on or about April 14,
2003, subject to customary closing conditions.


LEGG MASON WOOD WALKER
     INCORPORATED

               RBC CAPITAL MARKETS

                               STIFEL, NICOLAUS & COMPANY
                                      INCORPORATED

                                               HOWE BARNES INVESTMENTS, INC.




                The date of this Prospectus is April 9, 2003






                           ALLEGIANT BANCORP, INC.

               ST. LOUIS METROPOLITAN AREA BANKING FACILITIES


                                    [MAP]












              [The inside front cover of the prospectus depicts
          a map of the metropolitan St. Louis service territory of
                Allegiant Bank showing its branch locations.]











                              TABLE OF CONTENTS

                                                                        PAGE
                                                                        ----
                                                                     
ABOUT THIS PROSPECTUS.....................................................i
PROSPECTUS SUMMARY........................................................1
RISK FACTORS..............................................................8
CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS................13
USE OF PROCEEDS..........................................................14
MARKET FOR COMMON STOCK AND DIVIDENDS....................................14
CAPITALIZATION...........................................................16
MANAGEMENT...............................................................18
STOCK OWNERSHIP OF MANAGEMENT AND PRINCIPAL SHAREHOLDERS.................21
DESCRIPTION OF CAPITAL STOCK.............................................23
UNDERWRITING.............................................................25
LEGAL MATTERS............................................................27
EXPERTS..................................................................27
WHERE YOU CAN FIND ADDITIONAL INFORMATION................................27
INCORPORATION BY REFERENCE...............................................28



                            ABOUT THIS PROSPECTUS

         You should rely only on the information contained in this
prospectus or incorporated by reference into this prospectus. We have not,
and the underwriters have not, authorized any other person to provide you
with different information. The information contained in this prospectus is
accurate only as of the date of this prospectus, regardless of the time of
delivery of this prospectus or of any sale of common stock. Unless otherwise
indicated, all information in this prospectus assumes that the underwriters
will not exercise their option to purchase additional shares of common stock
to cover over-allotments.

          We sometimes refer to Allegiant Bank as the "bank." To understand
this offering fully, you should read this entire document carefully, including
particularly the "Risk Factors" section, as well as the documents identified
in the section titled "Where You Can Find Additional Information."


                                     i









               (This page has been left blank intentionally.)







                             PROSPECTUS SUMMARY

         This summary highlights information contained elsewhere in, or
incorporated by reference into, this prospectus. Because this is a summary,
it may not contain all information that may be important to you. Therefore,
you should read the entire prospectus, our financial statements, including
the related notes, and the other information that is incorporated by
reference into this prospectus before making a decision to invest in our
common stock.

                           ALLEGIANT BANCORP, INC.

         We are the largest publicly-held bank holding company headquartered
in the St. Louis metropolitan area. Our principal subsidiary, Allegiant
Bank, offers full-service banking and personal trust services to
individuals, businesses and municipalities in our market area. These
services include commercial real estate, commercial business and consumer
loans, checking, savings and time deposit accounts, wealth management and
other fiduciary services, as well as other financial services, including
mortgage banking, securities brokerage and insurance products. As of
December 31, 2002, we reported, on a consolidated basis, total assets of
$2.4 billion, loans of $1.7 billion and shareholders' equity of $167.2
million. This represents growth of 10.8%, 19.9% and 21.1%, respectively, when
compared to our total assets, loans and shareholders' equity as of December
31, 2001.

                            THE ST. LOUIS MARKET

         The St. Louis metropolitan area is the 18th largest metropolitan
market in the United States with a population of approximately 2.5 million.
The St. Louis area is home to 15 Fortune 1000 companies, including
Anheuser-Busch Companies, Inc., Emerson Electric Co. and The May Department
Stores Company. Over the past several years, a number of financial
institutions in our market area have been acquired by larger regional or
national out-of-town financial institutions. These acquisitions have
included: Marshall & Ilsley Corporation's 2002 acquisition of Mississippi
Valley Bancshares, Inc., Firstar Corporation's (now operating as U.S.
Bancorp) 1999 acquisition of Mercantile Bancorporation Inc., Union Planters
Corporation's 1998 acquisition of Magna Group, Inc. and NationsBank
Corporation's (now operating as Bank of America Corporation) 1997
acquisition of Boatmen's Bancshares, Inc. We believe we have capitalized on
opportunities created by this market consolidation and have built a strong,
customer-friendly, community-focused banking franchise.

                           KEY OPERATING STRENGTHS

         We believe the following operating strengths distinguish us from
our competition and position us for further growth and enhanced
profitability:

         o Growth in our market. Our primary goal has been to expand our
branch network in the St. Louis market while increasing our earnings per
share. Since our inception in 1989, we have grown through a combination of
internal growth and acquisitions. We have sought to maximize our internal
growth opportunities by positioning Allegiant as one of the leading St.
Louis community banks. From the beginning of 2000 to the end of 2002,
we estimate that our deposits and loans, excluding those added through
acquisitions, have grown at a compound annual rate of approximately
16.4% and 19.9%, respectively. From the beginning of 1998 to the end
of 2002, our diluted earnings per share have increased at a compound
annual rate of 22.1%. We cannot assure you that we will continue to
grow at historical rates or, to the extent we continue to grow,
that we will be able to adequately and profitably manage our growth. We
discuss factors that may negatively affect our future results under "Risk
Factors--Difficulties in managing operating risks resulting from our growth
may adversely affect our earnings and financial condition," "--Future growth
through acquisitions may subject us to special risks which may negatively
affect our earnings per share and our financial condition," and "--It may

                                     1



be difficult for us to maintain our historical growth rate, which may
adversely impact our results of operations."

         We have supplemented our internal growth with several acquisitions
within our market area. Since 2000, we have completed a number of
significant acquisitions, including: Equality Bancorp, Inc., a
community-based thrift holding company with total assets of approximately
$300.4 million, in November 2000; Southside Bancshares Corp., a
community-based bank holding company with total assets of approximately
$804.9 million, in September 2001; and five branches from Guardian Savings
Bank with total deposits of $109.3 million, in December 2001. Additionally,
in order to diversify our operations and sources of income, in October 2002,
we acquired Investment Counselors, Incorporated, an investment advisory firm
with approximately $331.9 million of assets under management.


         Consistent with our focus on establishing and maintaining a strong
presence in the most attractive areas in the St. Louis market, in March 2003,
we sold Bank of Ste. Genevieve, one of our two subsidiary banks, to First
Banks, Inc. Bank of Ste. Genevieve operates two branches located outside
of the St. Louis metropolitan area and has total assets of approximately
$110.0 million. First Banks acquired Bank of Ste. Genevieve in exchange for
approximately 974,150 shares of our common stock held by First Banks. The
net assets of Bank of Ste. Genevieve as of the closing were approximately
$17.9 million which approximated the value of consideration we received.
As a result, we did not recognize any gain or loss as a result of the
transaction. First Banks held approximately 7.4% of our outstanding common
stock prior to the exchange and held approximately 1.5% of our common
stock immediately following the exchange.


         o Strong commercial lending franchise. In order to improve the
profitability of our banking operations, over the past several years we have
reduced the number of residential mortgages that we hold in our portfolio
and have increased the amount of higher yielding commercial loans. Since the
beginning of 1998, and in part as a result of opportunities that resulted
from the consolidation of the St. Louis banking market, we have hired 23
commercial lending professionals, including a senior credit officer, who
average more than 15 years of commercial lending experience in the St. Louis
metropolitan area. As these local loan officers have joined our banking
team, we have benefited from their existing customer relationships, as well
as their local banking expertise. Our target lending customers are small to
mid-sized businesses requiring credit ranging in size from $1.0 million to
$3.0 million. As a result of our relationship lending focus, we may make
larger loans based upon the needs of our business customers and consistent
with our loan policy and applicable laws and regulations. During the year
ended December 31, 2002, our commercial business loans grew 23.3%, from
$255.2 million to $314.7 million, and our demand deposit accounts grew 7.1%,
from $201.2 million to $215.5 million. Commercial business loans generally
involve a higher degree of risk than our other types of loans. These risks
are discussed under "Risk Factors--Our exposure to credit risk and loan
losses is increased because we focus on commercial real estate, commercial
business and construction lending, which could adversely affect our earnings
and financial condition."

         o Full-service, community banking focus. We focus on serving
customers with banking needs that no longer can be adequately served by
smaller local institutions but who still desire the personalized service
that larger, out-of-state institutions do not effectively provide. Our
community banking focus and streamlined management and decision-making
procedures allow us to respond quickly to the needs of our individual and
business customers and to tailor products and services to meet their needs.

         We seek to effectively meet the convenience and needs of customers
through our extensive branch network that provides our customers at least
one branch located within a 20-minute drive from all principal sectors of
the St. Louis metropolitan area. Our 37 branches and 59 ATMs throughout the
St. Louis metropolitan area also serve to increase recognition of the
Allegiant name. In addition, we have

                                     2




sought to further enhance our name recognition by serving as the official
bank of the St. Louis Rams football team since July 2000.

                                  STRATEGY

         We believe that our operating strengths and the following
strategies position us for further asset and earnings per share growth:

         o Maintain strong asset quality while growing our commercial loan
portfolio. While commercial loan growth is a priority, we remain focused on
asset quality. Although our asset quality has been negatively impacted to
some degree by our recent acquisitions, our ratio of non-performing assets
to total assets improved from 0.93% at December 31, 2001 to 0.68% at
December 31, 2002.

         o Continue to build our relationship-based sales culture. We foster
an internal sales culture focused on increasing the number of products that
we provide to our customers. Over the past several years, we have
significantly improved our internal measures of how many banking products or
services we sell to new customers in the first six months of our
relationship with those customers. This improvement has resulted from
various initiatives, including the recent implementation of an enhanced
customer relationship management system to monitor results.

         o Expand our core deposit base. Expansion of our core deposit base
will provide us with a cost-effective and stable source of funding for our
loan portfolio. We have improved our non-interest bearing deposits to total
deposits ratio from 10.0% at December 31, 2000 to 12.2% at December 31,
2002, which we attribute, to a significant extent, to our efforts to
cross-sell deposit services to our commercial customers. We will continue to
pursue strategies to increase our non-interest bearing deposits.

         o Increase our non-interest income. In order to diversify our
sources of income and to reduce our dependence on net interest income, we
are focused on increasing our non-interest income. Non-interest income as a
percentage of our combined net interest income and non-interest income has
increased from 17.0% in 2000 to 26.4% in 2002. Although our wealth management
division has not historically contributed a significant portion of our total
revenues, we believe that our acquisition of Investment Counselors,
Incorporated, in conjunction with the trust operation we acquired in the
Southside transaction, has positioned this division to contribute
meaningful revenues to our franchise in the future. These acquired operations
enable us to offer a more comprehensive selection of wealth management
products and services to our customers.

         o Maintain strong expense controls. We have implemented a company-
wide cost control initiative intended to enhance efficiencies throughout our
organization that we refer to as "Project 2004." In addition, we
consolidated our banking operations into one primary subsidiary, Allegiant
Bank, during 2002. Our increased concentration on cost control efforts is
reflected in the improvement of our efficiency ratio from 59.6% for the year
ended December 31, 2000 to 54.0% for the year ended December 31, 2002.

         We believe growth of our average branch size and the resulting
economies of scale contribute significantly to improving our efficiencies.
We have 14 branches that we have owned since December 31, 1999 and which
have not been combined with acquired branches. Average deposits per branch
at these locations increased from $37.5 million at December 31, 1999
to $56.3 million at December 31, 2002, which we believe reflects
the success of our strategy for achieving organic growth.

                                   3




                                PROJECT 2004

         In August 2002, we announced the launch of Project 2004. The
mission of Project 2004 is to improve our operating platform by leveraging
our acquisition expertise internally. We are approaching this project as if
we had acquired our own operations and have evaluated our systems and
strategies in order to enhance our delivery of products and services to
customers, to improve operating efficiencies and to provide increased revenue.
Based on our evaluations, we have undertaken improvement initiatives, several
of which have been completed.

         Of our major initiatives, we expect to realize increases in
incremental revenue, beginning in the second half of 2003, at a rate of more
than $750,000 annually from improvements in our retail banking sales
training, measurement and tracking, and of up to $1.0 million annually from
the implementation of a specialized marketing plan for our 11 smallest
branches by deposit size. Our new sales measurement and tracking systems
will improve management's ability to identify products and practices that
are most profitable to us and focus our sales efforts on those products and
practices. Our new training will improve our employees' ability to offer
products to new and existing customers and to implement our most profitable
practices. Our specialized marketing plan includes mail programs and special
promotions directed to current and prospective customers in an effort to
increase deposits at our smaller branches.

         In addition, in the first half of 2003 we will implement a new fee
structure, operating procedures and electronic processing systems from which we
expect to realize improvements in operating efficiencies and incremental revenue
at a rate of up to $1.0 million annually. Operating efficiencies we expect to
achieve include more efficient branch staffing, implementation of an automated
credit scoring system for consumer lending and streamlining a variety of
backroom functions such as loan document imaging. We expect to achieve increases
in incremental revenue through fees on new customer services, including an
overdraft protection program for electronic transactions. However, we cannot
assure you that we will be able to realize all of the estimated revenues or
efficiencies from our Project 2004 initiatives.

                               MANAGEMENT TEAM


         Our management team is comprised of experienced individuals who
average more than 15 years in the banking or financial services industries.
Currently, our directors and executive officers own approximately 25% of our
outstanding common stock. Upon the completion of this offering, our directors
and officers would own approximately 22% of our outstanding common stock.


                               *     *     *


         Our principal executive offices are located at 10401 Clayton Road,
St. Louis, Missouri 63131, and our telephone number is (314) 692-8800.

                                     4






                                                        THE OFFERING
                                                            
Common Stock Offered........................................   1,800,000 shares

Common Stock Outstanding After
         the Offering.......................................   17,031,627 shares

Use of Proceeds.............................................   We will contribute substantially all of the net proceeds of
                                                               this offering to the bank to strengthen its capital position,
                                                               to support its anticipated loan growth and for other general
                                                               corporate purposes. The bank will use a portion of the capital
                                                               contributed to temporarily reduce short-term indebtedness,
                                                               which may be reborrowed, if necessary, to fund loan growth.
                                                               We will use the remaining proceeds that are not contributed to
                                                               the bank for general corporate and working capital purposes.

Dividends...................................................   Our quarterly dividends for the year ended 2002 totaled $0.26
                                                               per share. On March 24, 2003, our Board of Directors declared
                                                               a dividend of $0.07 per share for the first quarter of 2003
                                                               payable on April 15, 2003 to our shareholders of record on
                                                               April 1, 2003.

Nasdaq National Market Symbol...............................   ALLE


         The number of shares of common stock offered assumes the
underwriters' over-allotment option is not exercised. If the over-allotment
option is exercised in full, we will offer, issue and sell an additional
270,000 shares, and the common stock outstanding after this offering will be
17,301,627 shares.

         The number of shares outstanding after this offering set forth
above does not give effect to 4,873,360 shares reserved for issuance
under our stock option plans, of which options to purchase 1,091,534
shares at a weighted average price of $13.62 were outstanding at March 21,
2003.


                                     5





                              FINANCIAL SUMMARY

         The following table sets forth certain historical financial data of
Allegiant and its subsidiaries on a consolidated basis. This table should be
read in conjunction with our historical consolidated financial statements
and related notes incorporated by reference in this prospectus.



                                                      AS OF OR FOR THE YEAR ENDED DECEMBER 31,
                                           -------------------------------------------------------------
                                               2002          2001         2000        1999        1998
                                               ----          ----         ----        ----        ----
                                                    (DOLLARS IN THOUSANDS, EXCEPT PER SHARE DATA)
                                                                                
CONDENSED STATEMENT OF INCOME
Interest income .........................  $   123,205   $    96,423   $   71,973  $   52,112  $   49,218
Interest expense ........................       58,307        55,481       40,521      26,601      27,267
                                           -----------   -----------   ----------  ----------  ----------
   Net interest income ..................       64,898        40,942       31,452      25,511      21,951
Provision for loan losses ...............        8,599         5,000        3,500       2,546       2,420
Other non-interest income ...............       23,321        14,803        6,462       4,843       9,324
Other non-interest expense ..............       47,671        30,070       22,582      18,762      21,295
                                           -----------   -----------   ----------  ----------  ----------
   Income before income taxes ...........       31,949        20,675       11,832       9,046       7,560
Provision for income taxes ..............       10,552         7,553        4,797       3,644       3,026
                                           -----------   -----------   ----------  ----------  ----------
   Net income ...........................  $    21,397   $    13,122   $    7,035  $    5,402  $    4,534
                                           ===========   ===========   ==========  ==========  ==========

PER SHARE DATA
Basic earnings per share (1) ............  $      1.36   $      1.26   $     1.09  $     0.84  $     0.72
Diluted earnings per share (1) ..........         1.33          1.24         1.08        0.83        0.68
Dividends declared ......................         0.26          0.24         0.22        0.20        0.12
Book value at period end ................        10.36          9.08         8.75        7.73        7.36
Weighted average basic shares
   outstanding ..........................   15,767,619    10,447,845    6,460,250   6,450,639   6,250,910

BALANCE SHEET
Total assets ............................  $ 2,404,316   $ 2,170,479   $1,135,724  $  728,492  $  596,274
Investment securities ...................      455,082       463,637      134,296      60,797      54,780
Loans ...................................    1,702,909     1,419,796      813,971     615,191     495,669
Deposits ................................    1,768,032     1,687,615      858,084     548,466     450,766
Borrowed funds ..........................      399,735       269,218      174,951     112,221      93,817
Guaranteed preferred beneficial
   interest in subordinated
   debentures ...........................       57,250        57,250       17,250      17,250          --
Shareholders' equity ....................      167,242       138,068       77,806      47,991      48,104
Allowance for loan losses ...............       19,567        18,905       11,433       8,315       6,442

SELECTED RATIOS
Performance Ratios:
   Return on average assets .............         0.96%         0.94%        0.83%       0.83%       0.73%
   Return on average equity .............        13.88         13.59        13.21       10.60       10.14
   Net interest rate margin .............         3.19          3.17         3.99        4.17        3.82
   Efficiency ratio .....................        54.04         53.94        59.56       61.81       68.07
   Total loans to total assets ..........        70.83         65.41        71.67       84.45       83.13
Asset Quality Ratios:
   Nonperforming loans to total loans ...         0.92%         1.39%        0.38%       0.10%       0.36%
   Nonperforming assets to total assets..         0.68          0.93         0.29        0.14        0.30
   Allowance for loan losses to total
     loans ..............................         1.15          1.33         1.40        1.35        1.30
   Allowance for loan losses to
     nonperforming assets ...............       120.41         94.15       344.99      807.28      362.32
   Allowance for loan losses to
     nonperforming loans ................       125.12         95.92       366.09    1,324.20      362.32
   Net charge-offs to average loans .....         0.51          0.48         0.19        0.12        0.25
Allegiant Bancorp Capital Ratios:
   Total risk-based capital .............         9.97         10.01        10.79       10.23        8.68
   Tier 1 risk-based capital ............         8.75          8.11         9.53        8.80        7.42
   Tier 1 leverage capital ..............         7.07          6.32         8.71        7.47        5.83
   Equity to assets ratio ...............         6.96          6.36         6.85        6.59        8.07
   Tangible equity to tangible assets ...         4.66          3.86         5.95        5.06        6.07


-----------
(1) Based on weighted-average common shares outstanding.


                                     6






                                                      AS OF OR FOR THE YEAR ENDED DECEMBER 31,
                                           -------------------------------------------------------------
                                               2002          2001         2000        1999        1998
                                               ----          ----         ----        ----        ----
                                                    (DOLLARS IN THOUSANDS, EXCEPT PER SHARE DATA)
                                                                                
Allegiant Bank Capital Ratios:
   Total risk-based capital..............        10.63         10.48        11.65       11.52       10.93
   Tier 1 risk-based capital.............         9.56          9.26        10.40       10.27        9.68
   Tier 1 leverage capital...............         7.78          7.62         9.50        8.89        7.61

OTHER DATA
Number of St. Louis metropolitan area
   branches at period period end (1).....           37            37           23          15          13


-----------
(1) Excludes two branches which we acquired in September 2001, that were
    sold in connection with the sale of Bank of Ste. Genevieve to First
    Banks, Inc. in March 2003.


         All share and per share amounts included above have been restated
to reflect (1) a five-for-four stock split effected in January 1998 and
(2) a six-for-five stock split effected in January 1999.

         Our efficiency ratio is the quotient of our other non-interest
expense over the sum of our net interest income and other non-interest
income.

                                     7





                                RISK FACTORS

         You should carefully consider the following risk factors before
purchasing the shares offered by this prospectus. There could be other
factors not listed below that may affect us.

OUR ALLOWANCE FOR LOAN LOSSES MAY NOT BE ADEQUATE TO COVER ACTUAL LOAN
LOSSES, WHICH MAY REDUCE OUR NET INCOME.

         Our loan customers may not repay their loans according to their
terms, and the customers' collateral securing the payment of their loans may
be insufficient to assure repayment. Credit losses are inherent in the
lending business and could harm our operating results.

         We make various assumptions and judgments about the collectibility
of our loan portfolio and provide an allowance for potential losses based on
a number of factors. If our assumptions are wrong, our allowance for loan
losses may not be sufficient to cover our loan losses. We may have to
increase the allowance in the future. Additions to our allowance for loan
losses would decrease our net income.

OUR EXPOSURE TO CREDIT RISK AND LOAN LOSSES IS INCREASED BECAUSE WE FOCUS ON
COMMERCIAL REAL ESTATE, COMMERCIAL BUSINESS AND CONSTRUCTION LENDING, WHICH
COULD ADVERSELY AFFECT OUR EARNINGS AND FINANCIAL CONDITION.

         Commercial real estate, commercial business and construction
lending generally involve a higher degree of credit risk than single-family
residential lending. These loans involve larger loan balances to a single
borrower or groups of related borrowers. These loans are also more
susceptible to a risk of loss during a downturn in the business cycle. The
underwriting, review and monitoring performed by our officers and directors
cannot eliminate all of the risks related to these loans.

         Commercial real estate loans are dependent, in large part, on
sufficient income from the property securing the loan to cover operating
expenses and loan payments. In addition, many commercial real estate loans
are not fully amortized over the loan period, but have balloon payments due
at maturity. A borrower's ability to make a balloon payment typically will
depend on being able to either refinance the loan or timely sell the
underlying property.

         Our commercial business loans are typically based on the borrower's
ability to repay the loan from the cash flow of the business. A business's
cash flow depends substantially on the success of the business itself. In
addition, the collateral securing the loans may depreciate over time, be
difficult to appraise and fluctuate in value based on the success of the
business.

         Risk of loss on a construction loan depends largely upon whether we
properly estimate construction costs and a property's value at completion of
construction. If the estimate of value is inaccurate, the value of the
property securing our loans may be insufficient to ensure full repayment
when completed through sale, a permanent loan or seizure of collateral.

ADVERSE CHANGES IN THE ECONOMIC CONDITIONS OF THE ST. LOUIS MARKET COULD
RESULT IN GREATER LOAN DEFAULTS AND DEVALUATION OF OUR COLLATERAL.

         Our success depends to a great extent upon the general economic
conditions of the St. Louis metropolitan area. Unlike larger banks that are
more geographically diversified, we primarily provide banking and financial
services to customers in the St. Louis metropolitan area. In particular, the
ability of the borrowers to repay and the value of collateral securing our
commercial real estate, commercial business and construction loans, may be
impacted by local economic conditions. Favorable economic conditions may not
always exist in our market.

DIFFICULTIES IN MANAGING OPERATING RISKS RESULTING FROM OUR GROWTH MAY
ADVERSELY AFFECT OUR EARNINGS AND FINANCIAL CONDITION.

         We have developed risk management policies and procedures to
monitor and manage operating risks in connection with our growth. Our risk
management methods may not be effective because we

                                     8





may have failed to properly identify our operating risks and because certain
of the risks that we will face in the future may be different in nature or
magnitude than those we have faced in the past.

FUTURE GROWTH THROUGH ACQUISITIONS MAY SUBJECT US TO SPECIAL RISKS WHICH MAY
NEGATIVELY IMPACT OUR EARNINGS AND OUR FINANCIAL CONDITION.

         Integrating acquired businesses poses operating risks such as:

         o  diversion of our management's time and attention;

         o  impairment of relationships with, and the loss of, key
            employees and customers; and

         o  incurrence of unexpected expenses from integrating previously
            disparate operations and personnel.

         In addition to operating risks, acquiring other financial
institutions or other businesses involves risks commonly associated with
acquisitions, including:

         o  exposure to unknown or contingent liabilities of an acquired
            financial institution or business;

         o  potential asset quality issues of an acquired financial
            institution or business;

         o  increases in leverage and decreases in liquidity if we borrow
            to finance an acquisition or to maintain an appropriate level
            of regulatory capital; and

         o  dilution to our shareholders if we use our common stock as
            consideration for the acquisition.

IT MAY BE DIFFICULT FOR US TO MAINTAIN OUR HISTORICAL GROWTH RATE, WHICH MAY
ADVERSELY IMPACT OUR RESULTS OF OPERATIONS.

         We have completed various acquisitions and opened additional
branches in the past few years that have significantly enhanced our rate of
growth. We may not continue to sustain this rate of growth or grow at all.
Competition for suitable acquisition candidates is intense. We may target
acquisition candidates that a variety of larger financial institutions with
substantially greater resources than us also may be interested in acquiring,
which may make it more difficult or expensive for us to acquire potential
candidates.

THE LOSS OF CERTAIN KEY PERSONNEL COULD ADVERSELY AFFECT OUR OPERATIONS.

         Our success depends in large part on retaining the services of a
limited number of our key management, lending and other banking personnel.
We will likely undergo a difficult transition period if we lose the services
of any of these individuals.

         Our success also depends on the experience of the managers of our
branches and our lending officers and on their relationships with the the
communities and the customers they serve. The loss of these key persons
could negatively impact the affected banking operations. We may not be able
to retain our current key personnel or attract additional qualified key
persons as needed.

CHANGES IN INTEREST RATES COULD ADVERSELY AFFECT OUR EARNINGS; AT PRESENT,
WE EXPECT THAT OUR ASSETS WOULD REPRICE FASTER THAN OUR LIABILITIES IN A
DECLINING INTEREST RATE ENVIRONMENT, RESULTING IN A DECREASE IN OUR NET
INTEREST INCOME IF MARKET INTEREST RATES DECLINE.

         Like other financial institutions, net interest income will affect
our results of operations. Net interest income is the difference between
interest earned on loans and investments and interest expense incurred on
deposits and other borrowings. Our net interest income will be impacted by
changes in market rates of interest, the interest rate sensitivity of our
assets and liabilities, prepayments on our loans and investments and limits
on increases in the rates of interest charged on our residential real estate
loans.

         Certain of our assets and liabilities may react in different
degrees to changes in market interest rates. In addition, interest rates on
some types of assets and liabilities may fluctuate prior to changes in

                                     9





broader market interest rates, while rates on other types may lag behind. We
continually take measures intended to manage the risks from changes in market
interest rates, including using derivatives and other interest-sensitive
instruments to manage our interest rate risk. These investments may not
perform as we anticipate and may not reduce interest rate exposure in the
manner or with the precision we intended. In addition, our position is
slightly asset-sensitive and, therefore, in a declining interest rate
environment, our net interest income will decrease because our assets will
reprice faster than our liabilities.

CHANGES IN INTEREST RATES ARE NOT PREDICTABLE AND MAY ADVERSELY AFFECT OUR
EARNINGS.

         We will not be able to predict or control changes in interest
rates. Market interest rates are affected by regional and local economic
conditions, as well as monetary policies of the Board of Governors of the
Federal Reserve. The following factors also may affect market interest
rates:

         o  inflation or deflation;

         o  slow or stagnant economic growth or recession;

         o  unemployment;

         o  money supply;

         o  international disorders;

         o  instability in domestic and foreign financial markets; and

         o  other factors beyond our control.

Market interest rates will impact the amounts earned on our assets such as
loans and securities and the amounts paid on our liabilities such as
deposits and borrowings.

OWNERSHIP OF OUR COMMON STOCK BY INSIDERS LIMITS THE ABILITY OF OTHER
SHAREHOLDERS TO EXERT CONTROL OVER OUR ORGANIZATION.


         Currently, our directors and executive officers own approximately
25% of our outstanding common stock. Upon the completion of this offering,
our directors and officers would own approximately 22% of our outstanding
common stock. As a result, these insiders will effectively control the
election of our Board of Directors and thus our direction and future
operations. Our other shareholders may therefore lack an effective vote
with respect to these matters.


WE CONTINUALLY ENCOUNTER TECHNOLOGICAL CHANGE, AND WE MAY HAVE FEWER
RESOURCES THAN MANY OF OUR COMPETITORS TO CONTINUE TO INVEST IN
TECHNOLOGICAL IMPROVEMENTS, WHICH COULD REDUCE OUR ABILITY TO EFFECTIVELY
COMPETE.

         The financial services industry is undergoing rapid technological
changes with frequent introduction of new technology-driven products and
services. In addition to better serving customers, the effective use of
technology increases efficiency and enables financial institutions to reduce
costs. Our future success will depend, in part, upon our ability to address
the needs of our customers by using technology to provide products and
services to enhance customer convenience, as well as to create additional
efficiencies in our operations. Many of our competitors have substantially
greater resources to invest in technological improvements. We cannot assure
you that we will be able to effectively implement new technology-driven
products and services, which could reduce our ability to effectively
compete.

COMPETITION FROM OTHER FINANCIAL INSTITUTIONS WHICH HAVE GREATER RESOURCES
OR WHICH ARE SUBJECT TO LESS REGULATION THAN US MAY ADVERSELY AFFECT OUR
PROFITABILITY.

         We operate in a competitive environment. In the St. Louis
metropolitan area, other commercial banks, savings and loan associations,
credit unions, finance companies, mutual funds, insurance companies, brokerage
and investment banking firms, investment advisers, financial planners and other

                                     10





financial intermediaries offer similar services. Many of these competitors
have substantially greater resources and lending limits and may offer certain
services that we do not currently provide. In addition, the extensive
regulations that govern us and our banks may not apply to some of our non-bank
competitors. Our profitability depends upon the ability of Allegiant Bank to
compete in our market area.

WE ARE SUBJECT TO EXTENSIVE AND CONSTANTLY CHANGING REGULATION WHICH
SIGNIFICANTLY AFFECTS OUR BUSINESS.

         The banking industry is heavily regulated under both federal and
state law. These regulations are primarily intended to protect depositors
and the Federal Deposit Insurance Corporation, not creditors or
shareholders. We and our non-bank subsidiaries also are subject to the
supervision of the Federal Reserve Board, in addition to other regulatory
organizations. Regulations affecting banks and financial services companies
undergo continuous change, and the ultimate effect of such changes cannot be
predicted. Federal and state governments may modify regulations and laws at
any time, and may enact new legislation. In addition to laws and regulations
affecting our banking business, compliance with other laws, including the
corporate governance standards set forth in the recently enacted
Sarbanes-Oxley Act of 2002, regulatory requirements and Nasdaq National
Market standards impose administrative costs and burdens on us.

TERRORIST ATTACKS AND THREATS, ESCALATION OF MILITARY ACTIVITY IN RESPONSE
TO SUCH ATTACKS OR ACTS OF WAR MAY NEGATIVELY AFFECT OUR EARNINGS AND
FINANCIAL CONDITION.

         Our business is affected by general economic conditions,
fluctuations in consumer confidence and spending, and market liquidity,
which can decline as a result of numerous factors outside of our control,
such as terrorist attacks and acts of war. The deterioration of the domestic
economy could cause an increase in delinquencies in our loan portfolio and
loan losses. Future terrorist attacks, like the 2001 attacks in the United
States, as well as events occurring in response to, or in connection with,
the attacks, including rumors or threats of war, actual conflicts involving
the United States or its allies, or military disruptions could materially
adversely affect our business, financial condition and results of operations.

MANAGEMENT HAS DISCRETIONARY USE OF THE PROCEEDS OF THIS OFFERING.

         We will contribute substantially all of the net proceeds of this
offering to the bank to strengthen its capital position, to support its
anticipated loan growth and for other general corporate purposes. The bank
will use a portion of the capital contributed to temporarily reduce
short-term indebtedness, which may be reborrowed, if necessary, to fund loan
growth. We will use the remaining proceeds that are not contributed to the
bank for general corporate and working capital purposes. Accordingly, our
management will have broad discretion over how to utilize the majority of
the net proceeds of this offering. You will be relying on the judgment of
our management regarding application of these proceeds.

THERE IS A LIMITED TRADING MARKET FOR OUR COMMON STOCK AND YOU MAY NOT BE
ABLE TO RESELL YOUR SHARES AT OR ABOVE THE PRICE YOU PAY FOR THEM.

         The price of our common stock that you purchase in this offering
may decrease significantly. Our common stock is quoted on the Nasdaq
National Market under the symbol "ALLE." A public trading market having the
desired characteristics of liquidity and order depends on the presence in
the market of willing buyers and sellers at any given time. While each of
the underwriters is currently a market maker in our common stock on the
Nasdaq National Market, none of them is obligated to remain a market maker.
The presence of willing buyers and sellers depends on the individual
decisions of investors and general economic conditions, all of which are
beyond our control.


                                     11





FUTURE SALES OF SHARES OF OUR COMMON STOCK IN THE PUBLIC MARKET, OR THE
PERCEPTION THAT SUCH SALES MAY OCCUR, MAY DEPRESS OUR STOCK PRICE.

         If our existing shareholders sell our common stock in the public
market following this offering, or if there is a perception that these sales
may occur, the market price of our common stock could decline. Following
completion of this offering, our directors and executive officers will own
approximately 3.8 million shares of common stock (not including shares
issuable upon the exercise of options or restricted securities) that are
tradable in the public market, subject to limited restrictions imposed by
federal securities laws, beginning 180 days after this offering. In addition,
our Board of Directors has the authority to issue up to 20% more shares of our
authorized but unissued common stock without the vote of our shareholders.
Additional issuances of our common stock would dilute the percentage ownership
of existing shareholders and may dilute the per share book value of our common
stock.

ANTI-TAKEOVER PROVISIONS MAY DELAY OR PREVENT AN ACQUISITION BY A THIRD
PARTY.

         Provisions in our Restated Articles of Incorporation and Bylaws and
the corporate laws of the State of Missouri may discourage potential
acquisition proposals and could delay or prevent a change in control. These
provisions include a staggered board, a supermajority voting requirement for
certain mergers and asset sales and the right of our Board of Directors to
consider the interests of non-shareholder constituencies in connection with
acquisition proposals. Furthermore, federal banking laws and regulations
require the Federal Reserve Board's approval prior to acquisition of
"control" of a bank holding company. These provisions, laws and regulations
could delay or prevent a transaction that might otherwise result in a
premium over then-current market prices for holders of our shares, and may
limit the ability of our shareholders to approve transactions that they may
deem to be in their best interests.

OUR ABILITY TO PAY DIVIDENDS ON OUR COMMON STOCK IS LIMITED.

         Our ability to pay dividends on our common stock largely depends on
our receipt of dividends from our bank. The amount of dividends that our
bank may pay to us is limited by federal and state banking laws and
regulations which require the bank to satisfy certain capitalization
requirements. Moreover, we may decide to limit the payment of dividends even
when we have the legal ability to pay dividends in order to retain earnings
for use in our business. In addition, if interest payments required in
connection with trust preferred securities issued by two of our subsidiaries
are not made or suspended or if we fail to comply with certain covenants
under our term loan agreement, we are contractually prohibited from paying
dividends on our common stock.


                                     12




          CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

         This prospectus includes forward-looking statements. We have based
these forward-looking statements on our current expectations and projections
about future events. These forward-looking statements are subject to risks,
uncertainties and assumptions, including, among other things:

         o  the results of our efforts to implement our business strategy,
            including Project 2004;

         o  adverse changes in the bank's loan portfolio and the resulting
            credit risk-related losses and expenses;

         o  our ability to manage our growth, including the successful
            expansion of the customer support, administrative
            infrastructure and internal management systems necessary to
            manage that growth;

         o  our ability to attract core deposits;

         o  adverse changes in the economy of our market area that could
            increase credit-related losses and expenses;

         o  adverse changes in real estate market conditions that could
            negatively affect credit risk;

         o  the consequences of continued bank acquisitions and mergers in
            our market area, resulting in fewer but much larger and
            financially stronger competitors, which could increase
            competition for financial services to our detriment;

         o  fluctuations in interest rates and market prices, which could
            negatively affect net interest margins, asset valuations and
            expense expectations;

         o  changes in regulatory requirements of federal and state
            agencies applicable to bank holding companies and our present
            and future bank subsidiaries;

         o  changes in accounting principles;

         o  general economic conditions;

         o  other factors discussed in the "Risk Factors" section of this
            prospectus; and

         o  other risks and uncertainties detailed from time to time in our
            filings with the Securities and Exchange Commission.

         We undertake no obligation to publicly update or otherwise revise
any forward-looking statements, whether as a result of new information,
future events or otherwise. In light of these risks, uncertainties and
assumptions, the events discussed in any forward-looking statements in this
prospectus might not occur.


                                     13




                               USE OF PROCEEDS


         The net proceeds to us from the sale of the 1,800,000 shares of
our common stock will be approximately $27.7 million ($31.9 million if the
underwriters' over-allotment option is exercised in full), after deducting
the underwriting discount and estimated offering expenses of $325,000.


         We will contribute substantially all of the net proceeds of this
offering to the bank to strengthen its capital position, to support its
anticipated loan growth and for other general corporate purposes. The bank
will use a portion of the contributed capital to temporarily reduce
short-term indebtedness, including the borrowings currently outstanding
under a credit facility with the Federal Home Loan Bank, which may be
reborrowed, if necessary, to fund loan growth. The borrowings to be repaid
accrue interest at a weighted average rate of 6.1% per annum and have a
weighted average maturity of approximately seven months. The bank also may use
a portion of the net proceeds to open new branches or acquire businesses or
branch locations in the future. Other than an agreement to acquire a St. Louis
branch of Heartland Bank with approximately $23.5 million in related deposit
liabilities, we have no present understandings or agreements or definitive
plans relating to any specific acquisitions. We intend to use any remaining
proceeds not contributed to the bank for general and working capital purposes.

         We have not yet determined the amount of net proceeds to be used
specifically for each of the foregoing purposes. Accordingly, our management
will have significant flexibility in applying the net proceeds from this
offering. Pending their use as described above, we may invest the net
proceeds from this offering in bank-qualified investments.


                    MARKET FOR COMMON STOCK AND DIVIDENDS

         Our common stock is listed for quotation on the Nasdaq National
Market under the symbol "ALLE." As of March 21, 2003, there were 1,697
shareholders of record of our common stock.


         Set forth below are the high and low last sale prices for our
common stock (as reported by the Nasdaq National Market) for each quarter of
2001, 2002 and 2003 (through April 8, 2003) as well as the amount of cash
dividends per share we declared in each quarter.



                                                                     HIGH      LOW    DIVIDEND
                                                                     ----      ---    --------
                                                                              
YEAR ENDED DECEMBER 31, 2001
    First Quarter..............................................     $11.31   $ 8.88    $0.060
    Second Quarter.............................................      12.73     9.60     0.060
    Third Quarter..............................................      14.99    10.53     0.060
    Fourth Quarter.............................................      13.81    11.40     0.060

YEAR ENDED DECEMBER 31, 2002
    First Quarter..............................................     $17.50   $13.45    $0.065
    Second Quarter.............................................      19.00    15.72     0.065
    Third Quarter..............................................      18.80    15.02     0.065
    Fourth Quarter.............................................      18.24    15.99     0.065

YEAR ENDING DECEMBER 31, 2003
    First Quarter..............................................     $18.34   $16.59    $0.070
    Second Quarter (through April 8, 2003).....................      17.07    16.98        --



                                    14




         On April 8, 2003, the closing sale price for our common stock,
as reported on the Nasdaq National Market, was $17.07 per share.


         In 2001, we declared four quarterly cash dividends on our common
stock of $0.060 per share, for an aggregate amount of approximately $2.1
million. In 2002, we declared four quarterly cash dividends on our common
stock of $0.065 per share, for an aggregate amount of approximately $4.0
million. On March 24, 2003 our board of directors declared a dividend of
$0.070 per share for the first quarter of 2003 that is payable on April 15,
2003 to our shareholders of record as of April 1, 2003. Purchasers of shares
in this offering will not be paid this dividend on the shares they purchase
in the offering.

         We generally declare and pay cash dividends quarterly. Because
substantially all of the funds available for the payment of cash dividends are
derived from the bank, future cash dividends will depend primarily upon the
bank's earnings, financial condition and need for funds, as well as government
policies and regulations applicable to the bank and us. As of December 31,
2002, the net profits of the bank available for distribution to us as dividends
without regulatory approval were approximately $70.6 million. If required
payments on outstanding trust preferred securities issued by two of our
subsidiaries are not made or suspended or if we fail to comply with certain
covenants under our term loan agreement, we will be prohibited from paying
dividends on our common stock.


                                     15




                               CAPITALIZATION



         The following tables set forth our unaudited consolidated
capitalization and regulatory capital ratios (1) at December 31, 2002, (2) on
a pro forma basis to reflect the March 2003 sale of our wholly-owned banking
subsidiary, Bank of Ste. Genevieve, to First Banks, Inc. in exchange for
974,150 shares of our common stock as if the transaction had been completed as
of December 31, 2002, and (3) on a pro forma basis to reflect the sale of Bank
of Ste. Genevieve to First Banks, Inc. as if the transaction had been
completed as of December 31, 2002 and on an as adjusted basis to reflect the
sale of 1,800,000 shares of common stock offered by us pursuant to this
prospectus at the public offering price of $16.50 per share and the
application of the estimated net proceeds from the sale. This information
should be read in conjunction with our consolidated financial statements and
notes thereto incorporated by reference in this prospectus.



                                                                                  DECEMBER 31, 2002
                                                                  ------------------------------------------------
                                                                                                        PRO FORMA
                                                                      ACTUAL         PRO FORMA(1)      AS ADJUSTED
                                                                     --------        ------------      -----------
                                                                     (DOLLARS IN THOUSANDS, EXCEPT PER SHARE DATA)
                                                                                               
INDEBTEDNESS
Bank borrowings................................................      $ 35,000          $ 35,000         $ 35,000
Other short-term borrowings....................................        59,882            59,882           59,882
Federal Home Loan Bank advances................................       304,853           303,239          303,239
Guaranteed preferred beneficial interest in
   subordinated debentures.....................................        57,250            57,250           57,250
                                                                     --------          --------         --------
   Total indebtedness..........................................      $456,985          $455,371         $455,371
                                                                     ========          ========         ========

SHAREHOLDERS' EQUITY
Common stock, $0.01 par value; 30,000,000 shares authorized;
   16,146,804 shares outstanding actual; 15,172,654 shares
   pro forma; 16,972,654 shares pro forma as adjusted (2)......      $    161          $    152         $    170
Capital surplus................................................       119,933           119,791          147,455
Retained earnings..............................................        44,614            45,132           45,132
Treasury stock, at cost; no shares outstanding actual; 974,150
   shares pro forma and pro forma as adjusted..................            --           (17,900)         (17,900)
Accumulated other comprehensive income.........................         2,534             2,167            2,167
                                                                     --------          --------         --------
   Total shareholders' equity..................................       167,242           149,342          177,024
                                                                     --------          --------         --------
Total capitalization...........................................      $224,492          $206,592         $234,274
                                                                     ========          ========         ========

Book value per share...........................................      $  10.36          $  10.01         $  10.59
Tangible book value per share (3)..............................      $   6.76          $   6.37         $   7.34


                                                                               DECEMBER 31, 2002
                                        "WELL-         -----------------------------------------------------------------
                                     CAPITALIZED"                                                         PRO FORMA
                                     STANDARD(4)              ACTUAL               PRO FORMA             AS ADJUSTED
                                ---------------------  --------------------  --------------------   --------------------
                                ALLEGIANT   ALLEGIANT  ALLEGIANT  ALLEGIANT  ALLEGIANT  ALLEGIANT   ALLEGIANT  ALLEGIANT
                                  BANK       BANCORP     BANK      BANCORP     BANK      BANCORP      BANK      BANCORP
                                ---------   ---------  ---------  ---------  ---------  ---------   ---------  ---------
                                                                                       
CAPITAL RATIOS
Total risk-based capital ratio    10.00%       N/A      10.63%       9.97%    10.63%      9.47%      11.92%     10.90%
Tier 1 risk-based capital ratio    6.00        N/A       9.56        8.75      9.56       8.26       10.86       9.70
Tier 1 leverage capital ratio      5.00        N/A       7.78        7.07      7.78       6.76        8.87       7.94


(1) Pro forma information reflects the following adjustments in respect of
    the March 2003 sale of Bank of Ste. Genevieve:

    o   Federal Home Loan Bank advances have been reduced by $1,614 to
        reflect elimination of the advances drawn by Bank of Ste. Genevieve;

    o   Common stock has been reduced by $9 to adjust the par value of
        remaining shares outstanding;

(footnotes continued on following page)

                                     16





    o   Capital surplus has been: increased by $9 to offset the reduction in
        the par value of remaining shares outstanding; increased by $367 to
        offset the adjustment in accumulated other comprehensive income due
        to the elimination of Bank of Ste. Genevieve; increased by $17,900
        to reflect the market value of the Allegiant shares received in the
        sale; and decreased by $18,418 to reflect the elimination of Bank
        of Ste. Genevieve's shareholders' equity arising from the sale;

    o   Retained earnings have been increased by $518 to reflect the closing
        cash dividend to Allegiant provided under the sale agreement;

    o   Treasury stock has been increased $17,900 to reflect the market
        value of the Allegiant shares acquired in the sale; and

    o   Accumulated other comprehensive income has been decreased by $367 to
        reflect the elimination of Bank of Ste. Genevieve's accumulated
        other comprehensive income arising from the sale.

    As a result of the above adjustments, on a pro forma basis Allegiant's
    total indebtedness is reduced by $1,614 and its total shareholders'
    equity and capitalization are reduced by $17,900.

(2) The number of shares outstanding does not give effect to 4,873,360
    shares reserved for issuance under our stock option plans (of which
    options to purchase 877,711 shares at a weighted average price of
    $12.21 were outstanding).

(3) Tangible book value per share equals total assets, less intangible
    assets, including goodwill, divided by the number of shares outstanding
    or assumed to be outstanding.

(4) Reflects the minimum amount of capital necessary to meet the
    "well-capitalized" regulatory standard for banks. As of December 31,
    2002, we exceeded the minimum "well-capitalized" standard for all Tier 1
    leverage, Tier 1 risk-based capital and total risk-based capital ratios.
    Upon completion of this offering, we will meet the "well-capitalized"
    standard for all three risk capital measures.



                                     17




                                 MANAGEMENT

         The following table sets forth certain information regarding our
directors and executive officers:



NAME                                  AGE                             POSITION
----                                  ---                             --------
                                           
Marvin S. Wool.........................74        Chairman of the Board
Shaun R. Hayes.........................43        Director, President and Chief Executive Officer
Robert L. Chambers.....................41        Director
Leland B. Curtis.......................59        Director
Kevin R. Farrell.......................51        Director and Secretary
Richard C. Fellhauer...................61        Director
Leon A. Felman.........................68        Director
Douglas P. Helein......................51        Director
Michael R. Hogan.......................49        Director
C. Virginia Kirkpatrick................69        Director
Nancy C. Pechloff......................50        Director
Thomas M. Teschner.....................46        Director
Robert E. Wallace, Jr..................47        Director
John L. Weiss..........................48        Director
Lee S. Wielansky.......................51        Director
Jeffrey S. Schatz......................45        Executive Vice President and Chief Financial Officer
Paul F. Glarner........................54        Executive Vice President and Chief Lending Officer
Arthur E. Weiss........................43        Senior Vice President, Wealth Management
Thomas A. Daiber.......................45        Executive Vice President


         Marvin S. Wool has served as a director since March 1990 and as our
Chairman and Chairman of our bank since March 1992. From March 1992 through
1998, Mr. Wool served as our Chief Executive Officer. For more than the past
five years, Mr. Wool has served as the President and Chief Executive Officer
of Dash Multi-Corp, Inc., the holding company for subsidiary companies
that are in the chemical, cloth coating, carpet and rubber products
industries.

         Shaun R. Hayes has served as a director and our President since
1989 and became our Chief Executive Officer in January 1999. Additionally,
Mr. Hayes has served as a director of our bank since 1990, and as President
and Chief Executive Officer of our bank since May 1992.

         Robert L. Chambers has served as a director since December 2000.
Mr. Chambers has been President of Huntleigh Securities Corp., a securities
brokerage company, since September 2000. Prior to that time, he was Chief
Executive Officer of K.W. Chambers & Co., a regional, full-service
broker/dealer, for more than five years.

         Leland B. Curtis has served as a director since April 1996 and was
a director of our bank from May 2000 to November 2001. Mr. Curtis has been a
partner at Curtis, Oetting, Heinz, Garrett & O'Keefe, P.C., a law firm
located in St. Louis, Missouri, for more than five years.

         Kevin R. Farrell has served as a director since June 1989, as our
Secretary since 1994 and as a director of our bank since 1990. Mr. Farrell
has been President of Great Ledge Development, Inc., formerly St. Louis
Steel Products, Inc., a metal forming company, since its founding in 1990.

         Richard C. Fellhauer has served as a director since December 2000.
Mr. Fellhauer has been one of the bank's Senior Vice Presidents since
November 2000. Prior to that time, Mr. Fellhauer was the President, Chief
Executive Officer and Chairman of the Board of Equality Bancorp, the holding
company for Equality Savings Bank, from 1982 to November 2000.

         Leon A. Felman has served as a director since 1992 and as a
director of our bank since May 2000. Mr. Felman's business activities have
been private investment in financial institutions since 1999. For


                                     18




more than 30 years before that time, he was associated with Sage Systems,
Inc., a franchisee of Arby's restaurants in the St. Louis area, and served
as its President and Chief Executive Officer. Mr. Felman serves on the board
of directors of Dynex, Inc., a Richmond, Virginia-based mortgage real estate
investment trust listed on the New York Stock Exchange.

         Douglas P. Helein has served as a director since October 2001. Mr.
Helein has been an insurance broker for Welsch, Flatness & Lutz, Inc., an
insurance agency, for more than the past five years.

         Michael R. Hogan has served as a director since October 2000. Mr.
Hogan has been Chief Administrative Officer, Chief Financial Officer and
Vice President of Sigma-Aldrich Corporation, a life science company, since
April 1999. Prior to that time, he served three years as Corporate Vice
President and Controller for Monsanto Company, a St. Louis based
manufacturer of agriculture and biotechnology products and other consumer
products.

         C. Virginia Kirkpatrick has served as a director and as a director
of our bank since March 1990. Ms. Kirkpatrick has been President of CVK
Personal Management & Training Specialists, a business consulting and human
resource management firm, since 1982.

         Nancy C. Pechloff has served as a director since November 2002. Ms.
Pechloff has been an Adjunct Professor of Accounting at the Olin School of
Business at Washington University in St. Louis since September 2002. Prior
to that time, she was a Senior Audit Partner for 29 years at Arthur
Andersen LLP.

         Thomas M. Teschner has served as a director and as a director of
our bank since October 2001. Mr. Teschner has been a private investor since
October 2001. Prior to that time, he was the President and Chief Executive
Officer of Southside Bancshares Corp., the holding company for South Side
National Bank, from 1992 through September 2001.

         Robert E. Wallace, Jr. has served as a director since October 2000.
Mr. Wallace has been the Senior Vice President of Administration/General
Counsel of the St. Louis Rams, a professional football team, since 1995.

         John L. Weiss has served as a director since March 1999 and as a
director of our bank since May 1997. Mr. Weiss has been President of
Brentwood Volvo, an automobile dealership in St. Louis, Missouri, for more
than 15 years and has been the General Manager of Feld Toyota, an automobile
dealership located in St. Louis, since February 2000.

         Lee S. Wielansky has served as a director since 1990, was a
director of our bank from January 1999 to November 2001 and served as Vice
Chairman of our bank from February 1999 to November 2001. Mr. Wielansky has
been the President and Chief Executive Officer of JDN Development Company
since November 2000 and a member of its board of directors since February
2001. He has been a member of the board of directors of Acadia Realty, a New
York Stock Exchange-listed real estate investment trust, since June 2000.
Prior to that time, he was Managing Director of Investments and a
member of the board of directors of Regency Realty Corporation, a
publicly-held real estate investment trust, for more than three years.

         Jeffrey S. Schatz has served as one of our Executive Vice
Presidents and our Chief Financial Officer since February 2003. Prior to
becoming our Chief Financial Officer, Mr. Schatz served as our Chief
Operations Officer since January 2000. Prior to joining us, Mr. Schatz
served as Senior Vice President - Funds Management of Sky Financial Group,
Inc., a Bowling Green, Ohio bank holding company, for more than nine years.

         Paul F. Glarner has served as one of our Executive Vice Presidents
and our Chief Lending Officer since 1997. Prior to joining us, Mr. Glarner
served as an officer of Mercantile Bank, now U.S. Bank, for more than five
years.

                                     19





         Arthur E. Weiss has served as our Senior Vice President of Wealth
Management since 2000. Prior to joining us, Mr. Weiss served as the
President of The Weiss Group, Inc., an accounting and consulting firm. He
founded the firm in 1991 and sold it to a publicly-traded company in 1998.
From 1982 to 1991 Mr. Weiss was a tax manager with a Big 5 public accounting
firm.

         Thomas A. Daiber served as one of our Executive Vice Presidents
from May 1999 until March 2003. Mr. Daiber served as our Chief Financial
Officer from May 1999 until February 2003. In March 2003, Mr. Daiber resigned
from his Executive Vice President position to become Chairman, President and
Chief Executive Officer of Aviston Financial Corporation and Chairman and
Chief Executive Officer of the State Bank of Aviston in southwestern Illinois
on a full-time basis. Mr. Daiber was hired by us in March 1997 and served as
our Director of Internal Auditing prior to becoming our Chief Financial Officer.

                                     20




          STOCK OWNERSHIP OF MANAGEMENT AND PRINCIPAL SHAREHOLDERS

         The table below sets forth the beneficial ownership of our common
stock as of March 21, 2003, of each person we know to beneficially own 5% or
more of the common stock, each of our directors, the executive officers
named individually in our most recent proxy statement and all of our
directors and executive officers as a group. The number of beneficially
owned shares includes shares over which the named person, directly or
indirectly through any contract, arrangement, understanding, relationship or
otherwise, has or shares (1) voting power, which includes the power to vote,
or direct the voting of, such security; or (2) investment power, which
includes the power to dispose of, or to direct the disposition of, such
security. All shares of a named person are deemed to be subject to that
person's sole voting and investment power unless otherwise indicated. Shares
subject to stock options are included as outstanding shares of common stock,
except if these options are not exercisable within 60 days after March 21,
2003.



                                                                             NUMBER OF SHARES         PERCENT OF
NAME OF BENEFICIAL OWNER                                                  BENEFICIALLY OWNED (1)     COMMON STOCK
------------------------                                                  ----------------------     ------------
                                                                                                  
First Banks, Inc. (2)....................................................        1,205,929               7.4%
Robert L. Chambers (3)...................................................           32,945                 *
Leland B. Curtis (4).....................................................           58,860                 *
Kevin R. Farrell (5).....................................................          362,688               2.2
Richard C. Fellhauer (6).................................................          155,663               1.0
Leon A. Felman (7).......................................................        1,297,511               8.0
Shaun R. Hayes (8).......................................................          555,185               3.4
Douglas P. Helein (9)....................................................          310,722               1.9
Michael R. Hogan (10)....................................................           22,500                 *
C. Virginia Kirkpatrick (11).............................................          155,804               1.0
Nancy C. Pechloff (12)...................................................            2,679                 *
Thomas M. Teschner (13)..................................................          203,827               1.3
Robert E. Wallace, Jr. (14)..............................................           18,242                 *
John L. Weiss (15).......................................................           38,954                 *
Lee S. Wielansky (16)....................................................          153,628               1.0
Marvin S. Wool (17)......................................................          791,573               4.9
Jeffrey S. Schatz (18)...................................................           38,362                 *
Paul F. Glarner (19).....................................................           60,351                 *
Arthur E. Weiss (20).....................................................           22,935                 *
Thomas A. Daiber (21)....................................................           49,504                 *

All directors and executive officers as a group (19 persons) (22)........        4,331,932              25.9%


--------------
*     Less than 1%

(1)   Except as otherwise indicated, each individual has sole voting and
      investment power over the shares listed beside his or her name and is
      deemed to own shares issuable upon the exercise of stock options which
      were exercisable at March 21, 2003 or which were to become exercisable
      within 60 days thereafter. The percentage calculations for beneficial
      ownership are based upon 16,205,777 shares of our common stock that
      were issued and outstanding as of March 21, 2003, plus, with respect to
      each individual and for all directors and executive officers as a
      group, the number of shares subject to options that may be acquired
      upon exercise within 60 days after March 21, 2003.

(2)   First Banks, Inc.'s address is 135 North Meramec, Clayton, Missouri
      63105. The number of shares reported beneficially owned by First
      Banks, Inc. is based upon information furnished by our transfer agent,
      UMB Bank, n.a. In March 2003, First Banks, Inc. acquired our
      wholly-owned banking subsidiary, Bank of Ste. Genevieve, in exchange
      for approximately 974,150 shares of Allegiant common stock held by
      First Banks, Inc. Immediately after the transaction, First Banks, Inc.
      owned approximately 231,779 shares, or 1.5%, of our outstanding common
      stock.

(3)   Total includes 17,734 shares subject to stock options exercisable
      within 60 days.

(4)   Total includes 14,533 shares held jointly with Mr. Curtis's spouse,
      13,464 shares held in Mr. Curtis's IRA plan, 5,971 shares held in the
      Curtis, Oetting, et. al profit sharing plan, and 24,850 shares subject
      to stock options exercisable within 60 days.

(footnotes continued on following page)

                                     21




(5)   Total includes 196,509 shares held of record by Pentastar Family
      Holdings, Inc., 96,052 shares held of record by Cuttyhunk Investments,
      LLC, 1,771 shares held by Fidelity Investments as Trustee for the IRA
      of Mr. Farrell's spouse, 1,512 shares held by NFSC/FMTC as Trustee for
      the IRA of Mr. Farrell's spouse, 54,011 shares held by Fidelity
      Investments in Mr. Farrell's IRA plans, and 9,950 shares subject to
      stock options exercisable within 60 days.

(6)   Total includes 23,229 shares held jointly with Mr. Fellhauer's spouse,
      1,839 shares held by Mr. Fellhauer as custodian for his two children,
      3,661 shares held in the IRA account of Mr. Fellhauer's spouse, 77,171
      shares held subject to our section 401(k) plan, 23,035 shares held in
      Mr. Fellhauer's IRA plan, 383 shares held jointly with Michael Walsh,
      and 25,734 shares subject to stock options exercisable within 60 days.

(7)   Total includes 62,400 shares held in the Leon A. Felman Family Trust
      of which Mr. Felman is the voting trustee, 1,179,600 shares held in
      the Felman Family Partnership, LP of which Mr. Felman is the voting
      partner, and 5,000 shares subject to stock options exercisable within
      60 days. Mr. Felman's address is 2122 Kratky Road, St. Louis, Missouri
      63114.

(8)   Total includes 5,140 shares held for the benefit of Mr. Hayes's
      children as to which he has voting rights, 2 shares held of record by
      Mr. Hayes's spouse; 4,425 shares held subject to our section 401(k)
      plan, 21,000 shares of restricted stock, and 118,074 shares subject to
      stock options exercisable within 60 days.

(9)   Total includes 5,000 shares subject to stock options exercisable
      within 60 days.

(10)  Total includes 12,500 shares subject to stock options exercisable
      within 60 days.

(11)  Total includes 16,033 shares held jointly with Ms. Kirkpatrick's
      spouse, 3,015 shares held of record by Ms. Kirkpatrick's spouse,
      25,927 shares held in the IRA of Ms. Kirkpatrick's spouse, 7,118
      shares held jointly with Ms. Kirkpatrick's children, 9,950 shares held
      in Ms. Kirkpatrick's SEP account, and 14,950 shares subject to stock
      options exercisable within 60 days.

(12)  All shares are held as tenants by the entirety with Ms. Pechloff's spouse.

(13)  Total includes 23,958 shares held jointly with Mr. Teschner's spouse,
      and 5,000 shares subject to stock options exercisable within 60 days.

(14)  Total includes 5,741 shares held jointly with Mr. Wallace's spouse,
      and 12,500 shares subject to stock options exercisable within 60 days.

(15)  Total includes 3,256 shares held in the IRA account of Mr. Weiss's
      spouse, 723 shares held jointly with Mr. Weiss's spouse, 750 shares
      held jointly with Mr. Weiss's mother, 5,967 shares held in Mr. Weiss's
      IRA plan, and 18,094 shares subject to stock options exercisable
      within 60 days.

(16)  Total includes 24,850 shares subject to stock options exercisable
      within 60 days.

(17)  Total includes 76,005 shares held by the Dash Multi-Corp. Pension
      Plan, 63,636 shares held in trusts for the benefit of Mr. Wool's
      children, 11,216 shares held jointly with Mr. Wool's spouse, and
      47,845 shares subject to stock options exercisable within 60 days.

(18)  Total includes 1,162 shares held subject to our section 401(k) plan,
      3,000 shares held jointly with Mr. Schatz's spouse, 12,000 shares of
      restricted stock, and 22,200 shares subject to stock options
      exercisable within 60 days.

(19)  Total includes 4,522 shares held subject to our section 401(k) plan,
      111 shares held by Mr. Glarner as custodian for his daughter, 1,074
      shares held jointly with Mr. Glarner's spouse, 12,000 shares of
      restricted stock, and 39,000 shares subject to stock options
      exercisable within 60 days.

(20)  Total includes 4,000 shares held jointly with Mr. Weiss's spouse, 1,411
      shares held subject to our section 401(k) plan, 524 shares held in Mr.
      Weiss's IRA plan, 7,000 shares of restricted stock, and 10,000 shares
      subject to stock options exercisable within 60 days.

(21)  Total includes 1,299 shares held subject to our section 401(k) plan,
      5,250 shares of restricted stock, and 30,500 shares subject to stock
      options exercisable within 60 days.

(22)  Total includes 62,500 shares of restricted stock, and 444,381 shares
      subject to stock options exercisable within 60 days.


                                     22




                        DESCRIPTION OF CAPITAL STOCK

         The following summary description of our capital stock is qualified
in its entirety by reference to our Restated Articles of Incorporation and
Bylaws.


         We are authorized to issue 30,000,000 shares of common stock, $0.01
par value per share. As of March 21, 2003, there were 16,205,777 shares of
common stock outstanding and 4,873,360 shares reserved for issuance under
our stock option plans, of which options to purchase 1,091,534 shares at a
weighted average price of $13.62 were outstanding.


DIVIDEND RIGHTS

         The holders of our common stock are entitled to receive dividends
when, as and if declared by our Board of Directors, subject to the rights of
holders of then outstanding shares, if any, having preferences with respect
to dividends. Under Missouri law, we may not authorize and make
distributions if, after giving effect to the distribution,

         o   we would be unable to meet our debts as they become due in the
             usual course of business; or

         o   our total assets would be less than the sum of (1) our total
             liabilities plus, (2) the amount that would be needed, if we
             were to be dissolved at the time of distribution, to satisfy
             any preferential rights of shareholders upon dissolution
             superior to the rights of those shareholders receiving the
             distribution.

         If we do not make required payments on outstanding trust preferred
securities, or are in violation of certain covenants under our term loan
agreement, we are prohibited from paying dividends on our common stock.

         As a bank holding company, our ability to pay distributions will be
affected by the ability of our bank to pay dividends. Our ability, as well
as the ability of the bank, to pay dividends in the future currently is, and
could be further, influenced by bank regulatory requirements and capital
guidelines.

VOTING RIGHTS

         Except as described below regarding the election of directors, each
holder of common stock is entitled to one vote per share. The quorum for
shareholders' meetings is a majority of the outstanding shares entitled to
vote represented in person or by proxy.

PROVISIONS REGARDING CERTAIN BUSINESS COMBINATIONS

         Our Restated Articles of Incorporation require the affirmative vote
of the holders of at least 80% of the outstanding shares of our capital
stock to approve a merger and certain other business combinations involving
any holder of 5% or more of our common stock and us. However, if 75% or more
of the members of our Board of Directors approve the transaction, the
supermajority shareholder vote is not required.


         Currently, our directors and executive officers own approximately
25% of our outstanding common stock. Upon the completion of this offering,
our directors and officers would own approximately 22% of our outstanding
common stock. As a result, these insiders will effectively control the
election of our Board of Directors and thus our direction and future
operations, and our other shareholders may lack an effective vote with
respect to these matters. Consequently, the directors and executive officers
possess sufficient voting power to significantly affect the vote on, and
perhaps prevent, certain mergers and other business combinations.


ELECTION, CLASSIFICATION AND REMOVAL OF DIRECTORS

         Our Restated Articles of Incorporation provide for a classified
Board of Directors, with approximately one-third of the entire Board of
Directors being elected each year and with directors serving for terms of
three years. Directors are elected by a plurality of votes cast. Holders
of common

                                    23





stock have the right to cumulate their votes in the election of directors.
Our Restated Articles of Incorporation provide that any director, or the
entire Board of Directors, may be removed at any time by our shareholders,
without cause, by the affirmative vote of the holders of at least 80% of
the shares entitled to vote for the election of directors, and may be
removed for cause by an affirmative vote of a majority of the shares
entitled to vote.

SHAREHOLDER APPROVAL OF TRANSACTIONS

         An affirmative vote of at least 80% of the shares of our common
stock is required to amend the provisions of our Restated Articles of
Incorporation relating to the removal of a director or the approval
requirement for a merger or business combination with a holder of 5% or more
of our common stock. In addition, under Missouri law an affirmative vote of
at least two-thirds of the shares of our common stock is required to approve
a merger or sale of substantially all of our assets. Except for the
foregoing, any other proposal voted on by the shareholders will be approved
if the majority of the votes cast at the shareholders' meeting (at which a
quorum is present) called for the purpose of considering any such action are
cast in favor of the proposal.

LIQUIDATION RIGHTS

         In the event of our liquidation, dissolution or winding up, holders
of our common stock are entitled to receive equally and pro-rata per share
any assets distributable to shareholders, after payment of debts and
liabilities.

OTHER MATTERS

         Holders of our common stock do not have preemptive rights or
conversion rights with respect to our common stock. Except in connection
with certain business combinations and except as noted below, we can issue
new shares of authorized but unissued common stock without shareholder
approval. The bylaws of The Nasdaq Stock Market, Inc. governing the Nasdaq
National Market, on which our common stock is quoted, require issuers to
obtain shareholder approval for the issuance of securities in connection
with the acquisition of a business, company, assets, property or securities
representing such interests where the present or potential issuance of
common stock or securities convertible into common stock in connection with
such acquisition could result in an increase of 20% or more in the
outstanding shares of common stock. Accordingly, the future issuance of
common stock may require shareholder approval under those rules.

CERTAIN STATUTORY PROVISIONS

         We are subject to the business combination provisions under
Missouri law, which allow our Board of Directors to retain discretion over
the approval of certain business combinations. We are also subject to the
control shares acquisition provision under Missouri law, which places
restrictions on the voting rights of an acquiror with respect to any shares
of voting stock which increase its equity ownership to more than specified
thresholds unless certain conditions are satisfied. Missouri law also
permits our Board of Directors to consider the interests of non-shareholder
constituencies in connection with acquisition proposals. These provisions
may make it more difficult for there to be a change in control of us or
for us to enter into certain business combinations than if we were not
subject to these provisions.

TRANSFER AGENT

         UMB Bank, n.a., Kansas City, Missouri serves as the transfer agent
of our issued and outstanding common stock.


                                     24




                                UNDERWRITING


         Subject to the terms and conditions of an underwriting agreement,
the underwriters named below, for whom Legg Mason Wood Walker, Incorporated
is acting as representative, have severally agreed to purchase from us, and
we have agreed to sell to them, an aggregate of 1,800,000 shares of common
stock in the amounts set forth opposite each underwriter's name below:



                                                                    NUMBER OF
         UNDERWRITERS                                                SHARES
         ------------                                               ---------
                                                                 
         Legg Mason Wood Walker, Incorporated...................      792,000
         RBC Dain Rauscher Inc..................................      396,000
         Stifel, Nicolaus & Company, Incorporated...............      396,000
         Howe Barnes Investments, Inc...........................      216,000
                                                                    ---------
                  Total.........................................    1,800,000
                                                                    =========



         The underwriting agreement provides that the obligations of the
underwriters are subject to various conditions contained in the underwriting
agreement. If an underwriter defaults, the underwriting agreement provides
that the purchase commitments of the non-defaulting underwriters may be
increased or, in certain cases, that the underwriting agreement may be
terminated. The nature of the underwriters' obligation is such that they are
committed to purchase and pay for all of the shares of common stock (other
than those covered by the over-allotment option discussed below) if any are
purchased.


         We have granted the underwriters an option to purchase up to
270,000 additional shares of common stock at the same price per share to be
paid by the underwriters for the other shares of common stock being offered.
This option is exercisable from time to time for 30 days after the date of
this prospectus, but may be exercised by the underwriters only to cover any
over-allotments. If the underwriters elect to purchase any of the shares of
common stock under this option, each underwriter will be committed to
purchase the additional shares of common stock in approximately the same
proportion allocated to them in the table above.


         At our request, the underwriters have reserved up to 100,000 shares
of our common stock offered by this prospectus for sale to our directors and
officers at the public offering price set forth on the cover page of this
prospectus. These persons must commit to purchase no later than the close of
business on the day following the date of this prospectus. The number of
shares available for sale to the general public will be reduced to the
extent these persons purchase the reserved shares. We are not making loans
to these executive officers or directors to purchase such shares.

         We have agreed that, without the prior consent of the underwriters,
we will not directly or indirectly offer, sell or otherwise dispose of any
shares of common stock or any securities which may be converted into or
exchanged for common stock for a period of 180 days after the effective date
of the registration statement of which this prospectus is a part, subject to
certain exceptions. All of our executive officers and directors have agreed
that, without the prior written consent of the underwriters, they will not
directly or indirectly offer, sell or otherwise dispose of any shares of
common stock or any securities which may be converted into or exchanged for
common stock for a period ending 180 days after the effective date of the
registration statement of which this prospectus is a part, subject to
certain exceptions.

         The following table shows the public offering price, underwriting
discount and proceeds to us before expenses. Certain expenses of the
underwriters that are reimbursable by us are not included in

                                     25




the table. The information assumes either no exercise or full exercise by the
underwriters of their over-allotment option.




                                                  PER SHARE      WITHOUT OPTION      WITH OPTION
                                                  ---------      --------------      -----------
                                                                            
Public offering price.....................          $16.50         $29,700,000       $34,155,000
Underwriting discount.....................            0.94           1,692,000         1,945,800
Proceeds, before expenses.................           15.56          28,008,000        32,209,200


         The underwriters will initially offer the shares of common stock to
the public at the price stated on the cover page. The underwriters may offer
shares of common stock to selected dealers at the public offering price less
a concession of up to $0.57 per share. Those dealers may reallow a discount not
in excess of $0.10 per share to other brokers and dealers. After the initial
offering of the shares, the underwriters may change the offering price,
concession, discount and other selling terms.


         We estimate that we will spend approximately $325,000 for printing,
depository fees, legal and accounting fees and other expenses of the
offering in addition to the underwriting compensation.

         In connection with the offering, the underwriters and their
affiliates may engage in transactions, effected in accordance with the
Securities and Exchange Commission's Regulation M, that are intended to
stabilize, maintain or otherwise affect the market price of the common
stock. These transactions may include over-allotment or other mechanisms
through which the underwriters create a selling syndicate short position by
selling more shares of common stock than the underwriters are committed to
purchase. The underwriters may elect to cover any short position by
purchasing common stock in the open market or by exercising the
over-allotment option. The underwriters also may bid for, and purchase, the
common stock, including at a price above that which might otherwise prevail
in the open market for the purpose of preventing or retarding a decline in
the market price of the common stock. The underwriters may impose penalty
bids under which selling concessions allowed to syndicate members or other
dealers participating in the offering are reclaimed if shares of common
stock previously distributed in the offering are repurchased by the
underwriters. Any of these transactions may maintain or stabilize the price
for the common stock at a level above that which might otherwise prevail in
the open market. None of the underwriters or we make any representation or
prediction as to the direction or magnitude of any effect that the
transactions described above may have on the market price of the common
stock. The underwriters are not required to engage in any of these
transactions and may discontinue them at any time without notice if they
commence them. The underwriters may effect these transactions on the Nasdaq
National Market or elsewhere.

         The underwriters and selling group members may also engage in
passive market making transactions in the common stock in accordance with
Rule 103 of Regulation M. In general, a passive market maker may not bid for
or purchase shares of common stock at a price that exceeds the highest
independent bid. In addition, the net daily purchases made by any passive
market maker generally may not exceed 30% of its average daily trading
volume in the common stock or 200 shares, whichever is greater. A passive
market maker's bid size may not exceed the minimum quotation size for the
common stock or the market maker's remaining purchase capacity, whichever is
less. A passive market maker must identify passive market making bids as
such on the Nasdaq electronic inter-dealer reporting system. Passive market
making may stabilize or maintain the market price of the common stock above
independent market levels. Underwriters and dealers are not required to
engage in passive market making and may end passive market making activities
at any time.

         We have agreed to indemnify the underwriters against liabilities
arising from the offering of the shares of common stock, including civil
liabilities under the Securities Act of 1933, or to contribute to payments
that the underwriters may be required to make in connection with those
liabilities.

         Certain of the underwriters and their affiliates have provided in the
past and may provide in the future investment banking services for us or our
affiliates for which they would expect to receive


                                     26




customary fees and commissions. The underwriters are currently market makers
in our common stock on the Nasdaq National Market.

                                LEGAL MATTERS

         Our attorneys, Thompson Coburn LLP, St. Louis, Missouri, will opine
as to the validity of the common stock offered by us, as well as certain
other legal matters related to the sale of the shares. Certain legal matters
relating to the offering will be passed upon for the underwriters by Barack
Ferrazzano Kirschbaum Perlman & Nagelberg LLC, Chicago, Illinois.

                                   EXPERTS

         Our consolidated financial statements as of December 31, 2002 and
2001 and for each of the three years in the period ended December 31, 2002,
incorporated by reference in this prospectus and in the registration
statement, have been audited by Ernst & Young LLP, independent auditors, as
set forth in their report thereon incorporated by reference herein and in
the registration statement in reliance upon such report given on the
authority of that firm as experts in accounting and auditing.

                  WHERE YOU CAN FIND ADDITIONAL INFORMATION

         We are subject to the informational requirements of the Securities
Exchange Act of 1934. Accordingly, we file annual, quarterly and special
reports, proxy statements and other information with the Securities and
Exchange Commission. You may read and copy any document we file with the
Securities and Exchange Commission at the public reference facilities
maintained by the Securities and Exchange Commission at 450 Fifth Street,
N.W., Washington, D.C. 20549. Our filings with the Securities and Exchange
Commission also are available to the public from the Securities and Exchange
Commission's website at http://www.sec.gov. Please call the Securities and
Exchange Commission at 1-800-SEC-0330 for further information. Our common
stock is listed on the Nasdaq National Market. In addition, we maintain a
website at www.allegiantbank.com.

         This prospectus is part of a registration statement we filed with
the Securities and Exchange Commission and does not contain all of the
information set forth in the registration statement. You should consult the
registration statement for further information with respect to our company
and these securities.


                                     27





                         INCORPORATION BY REFERENCE

         The Securities and Exchange Commission allows us to "incorporate by
reference" the information we file with them, which means that we can
disclose important information to you by referring you to those documents.
The information incorporated by reference is considered to be part of this
prospectus, and later information that we file with the Securities and
Exchange Commission will automatically update and supersede this information
and information in this prospectus. We incorporate by reference the
documents listed below and any future filings made with the Securities and
Exchange Commission under Section 13(a), 13(c), 14 or 15(d) of the
Securities Exchange Act of 1934 until all of the securities are sold.

         o  Annual Report on Form 10-K for the year ended December 31, 2002
            (Commission File No. 000-10849);

         o  Portions of our Proxy Statement for our 2003 Annual Meeting of
            Shareholders (Commission File No. 000-10849) responsive to
            Items 5, 10, 11, 12 and 13 of Form 10-K;

         o  Portions of Allegiant Bancorp, Inc.'s 2002 Annual Report for
            Meeting of Shareholders filed as Exhibit 13 to our Annual
            Report on Form 10-K for the year ended December 31, 2002
            (Commission File No. 000-10849);

         o  Current Reports on Form 8-K filed March 28, 2003 (Commission
            File No. 000-10849) and April 2, 2003 (Commission File
            No. 000-10849); and

         o  The description of our common stock set forth in Item 11 of our
            Registration Statement on Form 10-SB (Reg. No. 0-26350), filed
            June 30, 1995.

         We will provide to each person, including any beneficial owner, to
whom a prospectus is delivered, a copy of any or all of the information that
has been incorporated by reference into the prospectus but not delivered
with the prospectus. You may request a copy of any of these filings, at no
cost, by writing or calling us at the following address: Secretary,
Allegiant Bancorp, Inc., 10401 Clayton Road, St. Louis, Missouri 63131,
telephone (314) 692-8800.

                                     28









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               (This page has been left blank intentionally.)







============================================================================


                              1,800,000 SHARES




                          [Allegiant Bancorp logo]




                                COMMON STOCK






                               ---------------

                                 PROSPECTUS

                               ---------------

LEGG MASON WOOD WALKER
     INCORPORATED

               RBC CAPITAL MARKETS

                               STIFEL, NICOLAUS & COMPANY
                                      INCORPORATED

                                               HOWE BARNES INVESTMENTS, INC.



                               April 9, 2003


============================================================================