SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                 SCHEDULE 13D/A
                    Under the Securities Exchange Act of 1934
                               (Amendment No. 1)*

                           INTROGEN THERAPEUTICS, INC.
                                (Name of Issuer)

                    COMMON STOCK, PAR VALUE $0.001 PER SHARE
                         (Title of Class of Securities)

                                   46119F 10 7
                                 (CUSIP Number)

                              Edward H. Stratemeier
                                 Vice President
                            Rhone-Poulenc Rorer, Inc.
                        300 Somerset Corporate Boulevard
                          Bridgewater, New Jersey 08807
                                  908-243-6000


            (Name, Address and Telephone Number of Person Authorized
                     to Receive Notices and Communications)

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

If the filing person has previously  filed a statement on Schedule 13G to report
the  acquisition  that is the subject of this  Schedule  13D, and is filing this
schedule because of Sections 240.13d-1(e),  240.13d-1(f) or 240.13d-1(g),  check
the following box [ ].

NOTE:  Schedules  filed in paper format shall include a signed original and five
copies of the schedule,  including all exhibits. See Section 240.13d-7 for other
parties to whom copies are to be sent.

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

The information required on 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).


                                       1


CUSIP No.  46119F 10 7
--------------------------------------------------------------------------------
1)   Name of Reporting Person:          Aventis Pharmaceuticals Inc.

     I.R.S. Identification Nos. of Above Persons (entities only):
     13-2563649
--------------------------------------------------------------------------------
2)   Check the Appropriate Box if a Member of a Group (See Instructions)
     (a)   [   ]
     (b)   [ X ]
--------------------------------------------------------------------------------
3)   SEC Use Only
--------------------------------------------------------------------------------
4)   Source of Funds (See Instructions)
     WC
--------------------------------------------------------------------------------
5)   Check if Disclosure of Legal Proceedings is Required Pursuant
     to Items 2(d) or 2(e)     [  ]
--------------------------------------------------------------------------------
6)   Citizenship or Place of Organization
     Delaware

--------------------------------------------------------------------------------
                  7)   Sole Voting Power
                       2,343,721 (1)
Number of         -------------------------------------------------------------
Shares            8)   Shared Voting Power
Beneficially           0
Owned by          -------------------------------------------------------------
Each              9)   Sole Dispositive Power
Reporting              2,343,721 (1)
Person With       -------------------------------------------------------------
                  10)  Shared Dispositive Power
                       0
--------------------------------------------------------------------------------
11)   Aggregate Amount Beneficially Owned by Each Reporting Person

      2,343,721
--------------------------------------------------------------------------------
12)   Check if the Aggregate Amount in Row (11) Excludes Certain
      Shares (See Instructions)    [  ]
--------------------------------------------------------------------------------
13)   Percent of Class Represented by Amount in Row (11)

      10.9% (2)
--------------------------------------------------------------------------------
14)   Type of Reporting Person (See Instructions)

      CO


                                       2


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

(1)  Represents 2,343,721 shares of common stock, par value $.001 per share (the
     "Common Stock") of Introgen  Therapeutics,  Inc. (the  "Company")  issuable
     upon conversion of Series A Non-Voting  Convertible  Preferred Stock of the
     Company  that  were  acquired  on July 2, 2001 by  Aventis  Pharmaceuticals
     Products Inc.,  which changed its name to Aventis  Pharmaceuticals  Inc. on
     December 31, 2001.

(2)  Beneficial ownership  percentages set forth herein assume that at as of the
     date  of  this  report,  there  were  21,442,382  shares  of  Common  Stock
     outstanding.  Pursuant to Rule 13d-3 under the Securities  Exchange Act, as
     amended,  2,343,721  shares of Common Stock issuable upon conversion of the
     Introgen Series A Non-Voting  Convertible  Preferred Stock and deemed to be
     beneficially  owned  by  the  reporting  person  are  also  assumed  to  be
     outstanding for purposes of computing these percentages.


                                       3


CUSIP No.  46119F 10 7
--------------------------------------------------------------------------------
1)    Name of Reporting Person:          Aventis Holdings Inc.

      I.R.S. Identification Nos. of Above Persons (entities only):
      57-0414396
--------------------------------------------------------------------------------
2)    Check the Appropriate Box if a Member of a Group (See Instructions)
      (a)  [   ]
      (b)  [ X ]
--------------------------------------------------------------------------------
3)    SEC Use Only
--------------------------------------------------------------------------------
4)    Source of Funds (See Instructions)
      AF
--------------------------------------------------------------------------------
5)    Check if Disclosure of Legal Proceedings is Required Pursuant
      to Items 2(d) or 2(e)     [  ]
--------------------------------------------------------------------------------
6)    Citizenship or Place of Organization
      Delaware

--------------------------------------------------------------------------------
                  7)   Sole Voting Power
                       6,312,614 (1)
Number of              ---------------------------------------------------------
Shares            8)   Shared Voting Power
Beneficially           0
Owned by               ---------------------------------------------------------
Each              9)   Sole Dispositive Power
Reporting              6,312,614 (1)
Person With            ---------------------------------------------------------
                  10)  Shared Dispositive Power
                       0
--------------------------------------------------------------------------------
11)   Aggregate Amount Beneficially Owned by Each Reporting Person

      6,312,614
-----------------------------------------------------------------------------
12)   Check if the Aggregate Amount in Row (11) Excludes Certain Shares
      (See Instructions)    [  ]
--------------------------------------------------------------------------------
13)   Percent of Class Represented by Amount in Row (11)

      29.4% (2)
--------------------------------------------------------------------------------
14)   Type of Reporting Person (See Instructions)

      CO


                                       4


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

(1)  Represents  direct ownership of 3,968,893 shares of Common Stock previously
     directly held by  Rhone-Poulenc  Rorer  International  (Holdings) Inc., and
     assigned  to its  affiliated  company  Aventis  Holdings  Inc. as part of a
     corporate  restructuring,  and  beneficial  ownership of the balance of the
     Subject Shares,  which are directly held by Aventis  Pharmaceuticals  Inc.,
     the  equity of which is 100%  owned by Aventis  Holdings  Inc.,  a Delaware
     corporation ("AHI").

(2)  Beneficial ownership  percentages set forth herein assume that at as of the
     date  of  this  report,  there  were  21,442,382  shares  of  Common  Stock
     outstanding.


                                       5


CUSIP No.  46119F 10 7
--------------------------------------------------------------------------------
1)    Name of Reporting Person:          Rhone-Poulenc Rorer, Inc.

      I.R.S. Identification Nos. of Above Persons (entities only):
      23-1699163
--------------------------------------------------------------------------------
2)    Check the Appropriate Box if a Member of a Group (See Instructions)
      (a)  [   ]
      (b)  [ X ]
--------------------------------------------------------------------------------
3)    SEC Use Only
--------------------------------------------------------------------------------
4)    Source of Funds (See Instructions)
      Not Applicable
--------------------------------------------------------------------------------
5)    Check if Disclosure of Legal Proceedings is Required Pursuant to
      Items 2(d) or 2(e)     [  ]
--------------------------------------------------------------------------------
6)    Citizenship or Place of Organization
      Pennsylvania

--------------------------------------------------------------------------------
                  7)   Sole Voting Power
                       6,312,614 (1)
Number of              ---------------------------------------------------------
Shares            8)   Shared Voting Power
Beneficially           0
Owned by               ---------------------------------------------------------
Each              9)   Sole Dispositive Power
Reporting              6,312,614 (1)
Person With            ---------------------------------------------------------
                  10)  Shared Dispositive Power
                       0
--------------------------------------------------------------------------------
11)   Aggregate Amount Beneficially Owned by Each Reporting Person

      6,312,614
--------------------------------------------------------------------------------
12)   Check if the Aggregate Amount in Row (11) Excludes Certain Shares
      (See Instructions)    [  ]
--------------------------------------------------------------------------------
13)   Percent of Class Represented by Amount in Row (11)

      29.4% (2)
--------------------------------------------------------------------------------
14)   Type of Reporting Person (See Instructions)

      CO


                                       6



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

(1)  Represents  beneficial ownership of shares held directly by AHI, the equity
     of  which  is 100%  owned  by  Rhone-Poulenc  Rorer  Inc.,  a  Pennsylvania
     corporation  ("RPR"),  and by  Aventis  Pharmaceuticals  Inc.,  a  Delaware
     corporation ("API"), the equity of which is 100% owned by AHI.

(2)  Beneficial ownership  percentages set forth herein assume that at as of the
     date  of  this  report,  there  were  21,442,382  shares  of  Common  Stock
     outstanding.  Pursuant to Rule 13d-3 under the Securities  Exchange Act, as
     amended,  2,343,721  shares of Common Stock issuable upon conversion of the
     Introgen Series A Non-Voting  Convertible  Preferred Stock and deemed to be
     beneficially  owned  by  the  reporting  person  are  also  assumed  to  be
     outstanding for purposes of computing these percentages.


                                       7


     This  Schedule  13D is filed to reflect  the  transfer of the shares of the
Common  Stock  solely  between  affiliated  companies  as  part  of a  corporate
restructuring.  The shares of Common Stock held by RPRIH were transferred to its
affiliated  entity,  AHI. As a result of the transfer AHI and RPR, both of which
are  affiliated  companies  of API,  and all of which  are  direct  or  indirect
subsidiaries  of Aventis  SA, a French  corporation,  have  acquired  beneficial
ownership of the Subject Shares.

     Also as  part  of this  corporate  restructuring  APPI  changed  it name to
Aventis Pharmaceuticals Inc.

     This  Schedule 13D also is filed to  incorporate  Exhibits  99.1,  99.2 and
99.3, which were previously omitted.

     This Amendment amends Item 5 and Item 7 only.

ITEM 5. INTEREST IN SECURITIES OF THE ISSUER.

     Item 5(b) is hereto amended and restated as follows:

     (b) The Reporting  Entity,  through its subsidiaries  Aventis Holdings Inc.
(with respect to the Original Introgen Shares) and Aventis  Pharmaceuticals Inc.
(with respect to the New Introgen Shares), has sole power to vote and to dispose
of the Subject Shares subject,  however, to the terms of the agreements referred
to in and incorporated by reference into Item 4 above.  Neither RPR, AHI nor API
nor, to the  knowledge of the  Reporting  Entity,  any of the persons  listed on
Exhibits  99.1 or 99.2 hereto has any power to vote or to direct the vote, or to
dispose of or to direct the  disposition  of, the Subject  Shares  except to the
extent to the extent  that any such  person may be deemed to have any such power
by  reason of such  person's  relationship  to or  position  with the  Reporting
Entity.


                                       8


ITEM 7. MATERIAL TO BE FILED AS EXHIBITS.

     1    Series A Non-Voting  Convertible  Preferred  Stock Purchase  Agreement
          dated as of June 30, 2001.

     2    Registration Rights Agreement dated as of June 30, 2001.

     3    Voting Agreement dated as of June 30, 2001.

     4    Series B Preferred  Stock  Purchase  Agreement  dated as of October 7,
          1994, as amended by Series C Preferred Stock Purchase Agreement.

     99.1 Information  concerning  directors and executive  officers of API, AHI
          and RPR.

     99.2 Information concerning members of the Supervisory Board and Management
          Board of Aventis SA.

     99.3 Agreement to File Jointly dated January 9, 2002, by and among API, AHI
          and RPR.


                                       9


                                   SIGNATURES

     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.

                                           AVENTIS PHARMACEUTICALS INC.



Date: January 9, 2001                      By:  /s/Edward H. Stratemeier
                                           Edward H. Stratemeier
                                           Vice President



     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.

                                           AVENTIS HOLDINGS INC.



Date:  January 9, 2002                     By:  /s/Phillip R. Ridolfi
                                           Phillip R. Ridolfi
                                           President



     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.


                                           RHONE-POULENC RORER INC.



Date: January 9, 2001                      By:  /s/Edward H. Stratemeier
                                           Edward H. Stratemeier
                                           Vice President


                                       10


                                INDEX OF EXHIBITS


  Exhibit
  Number                                 Description
  ------                                 -----------

     1        Series A Non-Voting Convertible Preferred Stock Purchase Agreement
              dated as of June 30,  2001 (filed with  Schedule  13D,  which this
              Amendment amends).

     2        Registration  Rights  Agreement  dated as of June 30,  2001 (filed
              with Schedule 13D, which this Amendment amends).

     3        Voting  Agreement  dated as of June 30, 2001 (filed with  Schedule
              13D, which this Amendment amends).

     4        Series B Preferred Stock Purchase Agreement dated as of October 7,
              1994, as amended by Series C Preferred  Stock  Purchase  Agreement
              (incorporated  by reference  from  Exhibits  10.33 and 10.5 to the
              Registration  Statement on Form S-1 of the Company  filed with the
              Securities and Exchange Commission (Registration No. 333-30582)).

     99.1     Information  concerning  directors and executive  officers of API,
              AHI and RPR (filed herewith).

     99.2     Information  concerning  members  of  the  Supervisory  Board  and
              Management Board of Aventis (filed herewith).

     99.3     Agreement to File Jointly dated January 9, 2002, by and among API,
              AHI and RPR (filed herewith).