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

                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934


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

                                  Common Stock
--------------------------------------------------------------------------------
                         (Title of Class of Securities)

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

                                December 31, 2001
--------------------------------------------------------------------------------
             (Date of Event Which Requires Filing of this Statement)

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

         / X /    Rule 13d-1(b)
         /   /    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 the section of the Act
but  shall be  subject  to all other  provisions  of the Act  (however,  see the
Notes).





                                  SCHEDULE 13G
                               CUSIP NO. 91307C102



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

         Quaker Capital Management Corporation
         -----------------------------------------------------------------------

2.       Check the Appropriate Box if a Member of a Group

         (a)
                  ------
         (b)        X
                  ------

3.       SEC Use Only
                                    --------------------------------------------

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

Number of         5.       Sole Voting Power                  336,300
  Shares                                                      ------------------
Beneficially      6.       Shared Voting Power                703,700
  Owned by                                                    ------------------
Each Reporting    7.       Sole Dispositive Power             336,300
  Person                                                      ------------------
   With:          8.       Shared Dispositive Power           703,700
                                                              ------------------

9.       Aggregate Amount Beneficially Owned by Each Reporting Person

         1,040,000
         ----------------

10.      Check if the Aggregate Amount in Row (9) Excludes Certain
         Shares
                        --------
         The Reporting Person disclaims beneficial ownership of 1,037,500 shares
owned by its clients.

11.      Percent of Class Represented by Amount in Row (9)
                                                             5.14%
                                                            --------

12.      Type of Reporting Person                              IA
                                                            --------------------



                               Page 2 of 7 Pages


                                  SCHEDULE 13G
                               CUSIP NO. 91307C102



Item 1.

         (a)      Name of Issuer

                  UNITED THERAPEUTICS CORPORATION
                  --------------------------------------------------------------

         (b)      Address of Issuer's Principal Executive Offices

                  1110 Spring Street, Silver Spring, MD 20910
                  --------------------------------------------------------------
Item 2.

         (a)      Name of Persons Filing

                  Quaker Capital Management Corporation
                  --------------------------------------------------------------

         (b)      Address of Principal Business Office or, if none,
                  Residence

                  401 Wood Street, Suite 1300, Pittsburgh, PA  15222
                  --------------------------------------------------------------

         (c)      Citizenship

                  Pennsylvania, USA
                  --------------------------------------------------------------

         (d)      Title of Class of Securities

                  Common Stock
                  --------------------------------------------------------------

         (e)      CUSIP Number

                  91307C102
                  --------------------------------------------------------------



                               Page 3 of 7 Pages



                                  SCHEDULE 13G
                               CUSIP NO. 91307C102


Item 3.   If this statement is filed pursuant to ss.240.13d-1(b) or 240.13d-2(b)
          or (c), check whether the person filing is a:

     (a)      /   /        Broker of dealer registered under section 15 of
                           the Act;

     (b)      /   /        Bank as defined in section 3(a)(6) of the Act;

     (c)      /   /        Insurance company as defined in section 3(a)(19)
                           of the Act;

     (d)      /   /        Investment company registered under section 8 of
                           the Investment Company Act of 1940;

     (e)      / X /        An investment adviser in accordance withss.240.13d-
                           1(b)(l)(ii)(E);

     (f)      /   /        An employee benefit plan or endowment fund in
                           accordance with ss.240.13d-1(b)(1)(ii)(F);

     (g)      /   /        A parent holding company or control person in
                           accordance with ss.240.13d-1(b)(1)(ii)(G);

     (h)      /   /        A savings association as defined in Section 3(b)
                           of the Federal Deposit Insurance Act;

     (i)      /   /        A church plan that is excluded from the definition
                           of an investment company under section 3(c)(14)
                           of the Investment Company Act of 1940;

     (j)      /   /        Group, in accordance with ss.240.13d-1((b)(l)(ii)(J)

Item 4.   Ownership
          ---------

     (a)  The Reporting  Person, in its capacity as investment  adviser,  may be
          deemed to be the  beneficial  owner of 1,037,500  shares of the Common
          Stock of the  Issuer  which are owned by various  investment  advisory
          clients of the  Reporting  Person in accounts over which the Reporting
          Person has  discretionary  authority.  The filing of this report shall
          not be  construed as an admission  that the  Reporting  Person is, for
          purposes of Section 13(d) or 13(g) of the Act, the beneficial owner of
          these  securities.  Additionally,  the  Reporting  Person  and/or  its
          principals  and  employees own 2,500 shares of the Common Stock of the
          Issuer.



                               Page 4 of 7 Pages



                                  SCHEDULE 13G
                               CUSIP NO. 91307C102


     (b)  The shares covered by this report  represent 5.14% of the Common Stock
          of the Issuer.

     (c)  The  Reporting  Person has shared  voting and  dispositive  power over
          703,700  shares and sole  voting and  dispositive  power over  333,800
          shares  owned by its clients  and held in  accounts  over which it has
          discretionary  authority.  The Reporting  Person and/or its principals
          and employees  have sole voting and  dispositive  power over the 2,500
          shares  owned  by the  Reporting  Person  and/or  its  principals  and
          employees.

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

          If this  statement  is being  filed to report  the fact that as of the
date hereof,  the reporting person has ceased to be the beneficial owner of more
than five percent of the class of securities, check the following: ----------

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

          1,037,500 of the shares with respect to which this report is filed are
owned by a variety of investment advisory clients of the Reporting Person, which
clients are entitled to receive  dividends on and the proceeds  from the sale of
such shares. No client is known to own more than 5% of the class.

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

          Not applicable.

Item 8.   Identification and Classification of Members of the Group

          Not applicable.

Item 9.   Notice of Dissolution of Group

          Not applicable.



                               Page 5 of 7 Pages


                                  SCHEDULE 13G
                               CUSIP NO. 91307C102

Item 10.  Certification

          By  signing  below I certify  that,  to the best of my  knowledge  and
belief,  the  securities  referred  to above were  acquired  and are held in the
ordinary  course  of  business  and 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 6 of 7 Pages




                                  SCHEDULE 13G
                               CUSIP NO. 91307C102


                                    SIGNATURE

                  After  reasonable  inquiry and to the best of my knowledge and
belief,  I certify  that the  information  set forth in this  statement is true,
complete and correct.


                                           QUAKER CAPITAL MANAGEMENT CORPORATION


                                                February 13, 2002
                                                --------------------------------
                                                         Date


                                                /s/ Mark G. Schoeppner
                                                --------------------------------
                                                         Signature


                                                Mark G. Schoeppner, President
                                                --------------------------------
                                                         Name/Title





                               Page 7 of 7 Pages