As filed with the Securities and Exchange Commission on July 14, 2005
                         Registration No.  333- ________
================================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C.  20549
                            _________________________

                                    FORM S-8
                          REGISTRATION STATEMENT UNDER
                           THE SECURITIES ACT OF 1933
                            _________________________

                           KNIGHT TRANSPORTATION, INC.
             (Exact name of Registrant as specified in its charter)


                ARIZONA                                86-0649974
                (State)                     (I.R.S. Employer Identification No.)

           5601 W. BUCKEYE RD.                           85043
            PHOENIX, ARIZONA                          (Zip Code)
(Address of Principal Executive Offices)


                        2003 KNIGHT TRANSPORTATION, INC.
                                STOCK OPTION PLAN
                            (Full title of the plan)
                            _________________________

                                  With copy to:

             Kevin P. Knight                     James E.  Brophy, III, Esq.
         Chief Executive Officer                 Ryley Carlock & Applewhite
        Knight Transportation, Inc.                      Suite 1200
          5601 West Buckeye Road                  One North Central Avenue
          Phoenix, Arizona 85043                   Phoenix, Arizona 85004
            (602) 269-2000                             (602) 258-7701
            (Name, address and telephone number of agent for service)
                            _________________________



                                      CALCULATION OF REGISTRATION FEE
==============================================================================================================
                                                    Proposed              Proposed
                                                    maximum               maximum
Title of securities to be      Amount to be    offering price per    aggregate offering        Amount of
registered                    registered (1)        share (2)             price (2)        registration fee(2)
--------------------------------------------------------------------------------------------------------------
                                                                              
Common stock, par value $.01
per share                       2,500,000           $25.825            $64,562,500.00          $7,599.01
==============================================================================================================


(1)  There  are  also  registered an undetermined number of additional shares of
     the  Company's  Common  Stock  that may become issuable under the Company's
     2003  Stock  Option Plan in the event of certain changes in the outstanding
     shares  of  the  Company's  Common Stock or in the capital structure of the
     Company,  including  any  stock  dividend, stock split, recapitalization or
     similar  transaction.

(2)  Estimated  solely  for  the  purpose  of  calculating the registration fee,
     pursuant  to  Rule  457(c) and 457(h) of the Securities Act of 1933, on the
     basis  of  the  average  of the high and low prices of the Company's Common
     Stock  on  the  New  York  Stock  Exchange  on  July  11,  2005.

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



                  EXPLANATORY NOTE; INCORPORATION BY REFERENCE

Knight  Transportation,  Inc.  (the "Registrant") has prepared this Registration
Statement  in  accordance with the requirements of Form S-8 under the Securities
Act of 1933 (the "Securities Act") to increase by 2,500,000 the number of shares
registered  under  the  2003  Knight  Transportation,  Inc.  Stock  Option Plan.
Pursuant  to General Instruction E of Form S-8, the contents of the Registration
Statement  on  Form  S-8  (File  No.  333-105718)  previously  filed  by  Knight
Transportation,  Inc.  with  the  Securities  and Exchange Commission on May 30,
2003,  are  hereby incorporated by reference in this Registration Statement.  In
accordance  with  the  instructions to Form S-8, the required legal opinions and
consents  are  attached  hereto.


                                      -2-

                                   SIGNATURES

     THE  REGISTRANT.  Pursuant  to  the  requirements  of the Securities Act of
     ---------------

1933, the Registrant certifies that it has reasonable grounds to believe that it
meets  all  of  the requirements for filing on Form S-8 and has duly caused this
Registration  Statement to be signed on its behalf by the undersigned, thereunto
duly  authorized,  in  the  City of Phoenix, State of Arizona, on this 12 day of
July, 2005.

                                        KNIGHT TRANSPORTATION, INC.,
                                        an Arizona corporation

                                        By    /s/  Kevin  P.  Knight
                                          --------------------------------------
                                          Kevin P. Knight, Chairman of the Board
                                          and Chief Executive Officer

                                        By    /s/ David Jackson
                                          --------------------------------------
                                          David Jackson, Chief Financial Officer

     Pursuant  to  the  requirements  of  the  Securities  Act  of  1933,  this
Registration  Statement  has  been  signed  by  the  following  persons  in  the
capacities  and  on  the  date  indicated.



            SIGNATURE AND TITLE                    DATE
            ------------------                     ----
                                                

/s/ Kevin P. Knight                                July 13, 2005
---------------------------------------
Kevin P. Knight, Chairman of the Board,
Director


/s/ Gary J. Knight                                 July 13, 2005
---------------------------------------
Gary J. Knight, Vice Chairman, Director


/s/ Timothy M. Kohl                                July 13, 2005
---------------------------------------
Timothy M. Kohl, Director, President


/s/ Donald A. Bliss                                July 12, 2005
---------------------------------------
Donald A. Bliss, Director


/s/ Randy Knight                                   July 13, 2005
---------------------------------------
Randy Knight, Director


/s/ G.D. Madden                                    July 12, 2005
---------------------------------------
G.D. Madden, Director


                                      -3-

/s/ Kathryn Munro                                  July 12, 2005
---------------------------------------
Kathryn Munro, Director


                                                   July __, 2005
---------------------------------------
Mark Scudder, Director

/s/ Michael Garnreiter                             July 12, 2005
---------------------------------------
Michael Garnreiter, Director



                                      -4-



                                  EXHIBIT INDEX
                                  -------------


                                                                      Sequentially
Exhibit No.                        Description                        Numbered Pages (1)
-----------                        -----------                        ------------------
                                                                
4.1          Articles 4, 10 and 11 of the Restated Articles of
             Incorporation of the Company.  (Incorporated by
             reference to Exhibit 4.1 to the Company's Registration
             Statement on form S-3 No. 333-72130)

4.2          Sections 2 and 5 of the Amended and Restated
             Bylaws of the Company.  (Incorporated by reference to
             Exhibit 4.2 to the Company's Registration Statement on
             form S-3 No. 333-72130)

4.3          Knight Transportation, Inc. 2003 Stock Option Plan.
             (Incorporated by reference from Exhibit 1 to the
             Company's Proxy Statement filed April 4, 2003 on
             Schedule 14A.)

5.1*         Opinion of Ryley Carlock & Applewhite, a
             professional association

23.1*        Consent of Ryley Carlock & Applewhite, a
             professional association (see Exhibit 5.1)

23.2*        Consent of Deloitte & Touche LLP, independent
             public accountants



* Filed herewith.

1/ The page numbers where exhibits (other than those incorporated by reference)
--
may be found are indicated only on the manually signed Registration Statement.



                                      -5-