UNITED STATES
                         SECURITIES EXCHANGE COMMISSION
                             Washington, D.C. 20549

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


                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934
                                (Amendment No. )

                         UNITED THERAPEUTICS CORPORATION
                         -------------------------------
                                (Name of Issuer)


                     Common Stock, par value $.01 per share
                     --------------------------------------
                         (Title of Class of Securities)


                                    91307C102
                                    ---------
                                 (CUSIP Number)


                                October 16, 2006
             -------------------------------------------------------
             (Date of Event which Requires Filing of this Statement)


Check the appropriate box to designate the rule pursuant to which this Schedule
is filed:

                             |_|  Rule 13d-1(b)

                             |X|  Rule 13d-1(c)

                             |_|  Rule 13d-1(d)

* The remainder of this cover page shall be filled out for a reporting  person's
initial filing on this form with respect to the subject class of securities, and
for any  subsequent  amendment  containing  information  which  would  alter the
disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the  Securities  Exchange  Act of
1934 ("Act") or otherwise  subject to the liabilities of that section of the Act
but  shall be  subject  to all other  provisions  of the Act  (however,  see the
Notes).


                          Continued on following pages
                                Page 1 of 9 Pages
                              Exhibit Index: Page 8




                                  SCHEDULE 13G

CUSIP No.: 91307C102                                           Page 2 of 9 Pages

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1.      Names of Reporting Persons.
        I.R.S. Identification Nos. of above persons (entities only).

        KINGDON CAPITAL MANAGEMENT, LLC
--------------------------------------------------------------------------------
2.      Check the Appropriate Box if a Member of a Group (See Instructions)

        (a)   |_|
        (b)   |_|
--------------------------------------------------------------------------------
3.      SEC Use Only

--------------------------------------------------------------------------------
4.      Citizenship or Place of Organization

        Delaware
--------------------------------------------------------------------------------
Number of            5.     Sole Voting Power                   1,150,000
Shares
Beneficially         -----------------------------------------------------------
Owned by Each        6.     Shared Voting Power                 0
Reporting
Person With          -----------------------------------------------------------
                     7.     Sole Dispositive Power              1,150,000

                     -----------------------------------------------------------
                     8.     Shared Dispositive Power            0
--------------------------------------------------------------------------------
9.      Aggregate Amount Beneficially Owned by Each Reporting Person

        1,150,000
--------------------------------------------------------------------------------
10.     Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See
        Instructions)

        [ ]
--------------------------------------------------------------------------------
11.     Percent of Class Represented by Amount in Row (9)

        5.0%
--------------------------------------------------------------------------------
12.     Type of Reporting Person (See Instructions)

        OO; IA



                                  SCHEDULE 13G

CUSIP No.: 91307C102                                           Page 3 of 9 Pages

--------------------------------------------------------------------------------
1.      Names of Reporting Persons.
        I.R.S. Identification Nos. of above persons (entities only).

        MARK KINGDON
--------------------------------------------------------------------------------
2.      Check the Appropriate Box if a Member of a Group (See Instructions)

        (a)   |_|
        (b)   |_|
--------------------------------------------------------------------------------
3.      SEC Use Only

--------------------------------------------------------------------------------
4.      Citizenship or Place of Organization

        United States of America
--------------------------------------------------------------------------------
Number of            5.     Sole Voting Power                   0
Shares
Beneficially         -----------------------------------------------------------
Owned by Each        6.     Shared Voting Power                 1,150,000
Reporting
Person With          -----------------------------------------------------------
                     7.     Sole Dispositive Power              0

                     -----------------------------------------------------------
                     8.     Shared Dispositive Power            1,150,000
--------------------------------------------------------------------------------
9.      Aggregate Amount Beneficially Owned by Each Reporting Person

        1,150,000
--------------------------------------------------------------------------------
10.     Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See
        Instructions)

        [ ]
--------------------------------------------------------------------------------
11.     Percent of Class Represented by Amount in Row (9)

        5.0%
--------------------------------------------------------------------------------
12.     Type of Reporting Person (See Instructions)

        HC




                                                               Page 4 of 9 Pages

Item 1(a).      Name of Issuer:

                United Therapeutics Corporation (the "Issuer").

Item 1(b).      Address of Issuer's Principal Executive Offices:

                1110 Spring Street, Silver Springs, MD  20910.

Item 2(a).      Name of Person Filing

                This Statement is filed on behalf of each of the following
persons (collectively, the "Reporting Persons"):

                i) Kingdon Capital Management, LLC ("Kingdon Capital
Management"); and

                ii) Mark Kingdon ("Mr. Kingdon").

                This  Statement  relates to Shares (as defined  herein) held for
the  accounts  of  Kingdon  Associates,  L.P.,  a New York  limited  partnership
("Kingdon  Associates"),  M. Kingdon  Offshore Ltd., a Cayman  Islands  exempted
company ("Kingdon Offshore"),  and Kingdon Family Partnership,  L.P., a New York
limited partnership ("Kingdon Family  Partnership").  Kingdon Capital Management
serves as investment manager to each of Kingdon Associates, Kingdon Offshore and
Kingdon Family Partnership.  In such capacity, Kingdon Capital Management may be
deemed  to have  voting  and  dispositive  power  over the  Shares  held for the
accounts of each of Kingdon  Associates,  Kingdon  Offshore  and Kingdon  Family
Partnership. Mr. Kingdon is the managing member and president of Kingdon Capital
Management.

Item 2(b).      Address of Principal Business Office or, if None, Residence

                The address of the principal business office of each of Kingdon
Capital Management and Mr. Kingdon is 152 West 57th Street, 50th Floor, New
York, New York 10019.

Item 2(c).      Citizenship

                i)  Kingdon Capital Management is a Delaware limited liability
                    company; and

                ii) Mr. Kingdon is a citizen of the United States of America.

Item 2(d).      Title of Class of Securities:

                Common Stock, par value $.01 per share (the "Shares").

Item 2(e).      CUSIP Number:

                91307C102




                                                               Page 5 of 9 Pages

Item 3.         If This Statement is Filed Pursuant to ss.ss.240.13d-1(b) or
                240.13d-2(b) or (c), Check Whether the Person Filing is a:

                This Item 3 is not applicable.

Item 4.         Ownership:

Item 4(a).      Amount Beneficially Owned:

                As of  November 6, 2006, each of Kingdon Capital  Management and
Mr.  Kingdon may be deemed to  beneficially  own 1,150,000  Shares.  This amount
consists of: (A) 228,600 Shares held for the account of Kingdon Associates;  (B)
80,600 Shares issuable upon the exercise of certain options held for the account
of  Kingdon  Associates;  (C)  584,800  Shares  held for the  account of Kingdon
Offshore;  (D) 206,500 Shares issuable upon the exercise of certain options held
for the account of Kingdon  Offshore;  (E) 36,600 Shares held for the account of
Kingdon Family Partnership;  and (F) 12,900 Shares issuable upon the exercise of
certain options held for the account of Kingdon Family Partnership.

Item 4(b).      Percent of Class:

                The number of Shares of which each of Kingdon Capital Management
and  Mr.  Kingdon  may  be  deemed  to  be  the  beneficial  owner   constitutes
approximately  5.0% of the  total  number  of  Shares  outstanding  (based  upon
information  provided by the Issuer in its most recent  quarterly report on Form
10-Q filed with the Securities and Exchange  Commission,  there were  22,937,972
Shares outstanding as of July 31, 2006).

Item 4(c).      Number of Shares of which such person has:

Kingdon Capital Management:
---------------------------

(i) Sole power to vote or direct the vote:                             1,150,000

(ii) Shared power to vote or direct the vote:                                  0

(iii) Sole power to dispose or direct the disposition of:              1,150,000

(iv) Shared power to dispose or direct the disposition of:                     0

Mr. Kingdon:
------------

(i) Sole power to vote or direct the vote:                                     0

(ii) Shared power to vote or direct the vote:                          1,150,000

(iii) Sole power to dispose or direct the disposition of:                      0

(iv) Shared power to dispose or direct the disposition of:             1,150,000


Item 5.         Ownership of Five Percent or Less of a Class:

                This Item 5 is not applicable.

Item 6.         Ownership of More than Five Percent on Behalf of Another Person:

                This Item 6 is not applicable.



                                                               Page 6 of 9 Pages

Item 7.         Identification and Classification of the Subsidiary Which
                Acquired the Security Being Reported on By the Parent Holding
                Company:

                See disclosure in Item 2 hereof.

Item 8.         Identification and Classification of Members of the Group:

                This Item 8 is not applicable.

Item 9.         Notice of Dissolution of Group:

                This Item 9 is not applicable.

Item 10.        Certification:

                By signing below each of the Reporting  Persons  certifies that,
to the best of their knowledge and belief, the securities referred to above were
not  acquired and are not held for the purpose of or with the effect of changing
or influencing the control of the issuer of the securities and were not acquired
and are not  held in  connection  with or as a  participant  in any  transaction
having that purpose or effect.


                                                               Page 7 of 9 Pages

                                    SIGNATURE

      After  reasonable  inquiry and to the best of their  knowledge and belief,
the  undersigned  certifies that the  information set forth in this statement is
true, complete and correct.

Date: November 6, 2006                     KINGDON CAPITAL MANAGEMENT, LLC


                                           By:    /s/ William Walsh
                                                 -------------------------------
                                           Name:  William Walsh
                                           Title: Chief Financial Officer

Date: November 6, 2006                     MARK KINGDON


                                           /s/ Mark Kingdon
                                           -------------------------------------



                                                               Page 8 of 9 Pages


                                  EXHIBIT INDEX


Ex.                                                                     Page No.
---                                                                     --------

A. Joint Filing Agreement, dated November 6, 2006 by and among Kingdon
   Capital Management, LLC and Mark Kingdon..........                         9




                                                               Page 9 of 9 Pages

                                    EXHIBIT A

                             JOINT FILING AGREEMENT

                The undersigned  hereby agree that the statement on Schedule 13G
with respect to the common stock of United Therapeutics  Corporation dated as of
November  6,  2006  is, and any  amendments  thereto  (including  amendments  on
Schedule  13D) signed by each of the  undersigned  shall be,  filed on behalf of
each of us pursuant to and in  accordance  with the  provisions of Rule 13d-1(k)
under the Securities Exchange Act of 1934, as amended.

Date: November 6, 2006                          KINGDON CAPITAL MANAGEMENT, LLC


                                                By: /s/ William Walsh
                                                   -----------------------------
                                                Name:  William Walsh
                                                Title: Chief Financial Officer

Date: November 6, 2006                          MARK KINGDON


                                                /s/ Mark Kingdon
                                                --------------------------------