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                                                                    Exhibit 10.1

                    FOURTH AMENDMENT TO EMPLOYMENT AGREEMENT

         This FOURTH AMENDMENT TO EMPLOYMENT AGREEMENT (the " Fourth Amendment")
made as of September 2, 2003, between ARIAD Pharmaceuticals, Inc., a Delaware
corporation (the "Company"), and Harvey J. Berger, M.D. (the "Employee").

         The Company and the Employee have entered into an Employment Agreement
dated as of January 1, 1992, as amended as of April 19, 1994, June 30, 1994, and
January 1, 1997 (the "Agreement"), and the parties hereto desire to further
amend certain provisions of the Agreement.

         NOW, THEREFORE, in consideration of the premises set forth herein and
for other good and valuable consideration, the receipt of which is hereby
acknowledged, the parties hereto agree to further amend the Agreement as
follows:

         I.       Termination of Employment. The first sentence of Section 2 is
hereby amended to read as follows:

                  "The term of the Employee's employment under this Agreement
         (the "Term") commenced as of January 1, 1992 (the "effective Date") and
         shall end on December 31, 2007, unless sooner terminated pursuant to
         Section 4 or 5 of this Agreement.

         II.      This Fourth Amendment shall be governed by and construed and
enforced in accordance with the laws of the Commonwealth of Massachusetts
applicable to agreements made and to be performed entirely in Massachusetts.

         III.     Except as modified by this Fourth Amendment, the Agreement
remains in full force and effect and unchanged.

                  IN WITNESS WHEREOF, the parties have executed this Fourth
Amendment as of the date first written above.

                                         ARIAD PHARMACEUTICALS, INC.

                                         By: /s/ Laurie A. Allen
                                            --------------------------------
                                            Laurie A. Allen, Esq.
                                            Corporate Secretary, Senior Vice
                                            President, Chief Legal Officer

                                         EMPLOYEE

                                            /s/ Harvey J. Berger
                                         -----------------------------------
                                         Harvey J. Berger, M.D.

                                       1<PAGE>

                                                                    Exhibit 10.2

                  FIRST AMENDMENT TO 2002 EMPLOYMENT AGREEMENT

         This AMENDMENT TO EMPLOYMENT AGREEMENT (the "First Amendment") made as
of September 2, 2003 between ARIAD Pharmaceuticals, Inc., a Delaware corporation
(the "Company"), and Laurie A. Allen, Esq., (the "Employee").

         The Company and the Employee have entered into a 2002 Employment
Agreement dated as of March 4, 2002 (the "Agreement"), and the parties hereto
desire to further amend certain provisions of the Agreement.

         NOW, THEREFORE, in consideration of the premises set forth herein and
for other good and valuable consideration, the receipt of which is hereby
acknowledged, the parties hereto agree to further amend the Agreement as
follows:

         I.       Term of Employment. The first sentence of Section 2 is hereby
amended to read as follows:

                  "The term of the Employee's employment under the Agreement is
         hereby extended to December 31, 2006 (the "Term"), unless sooner
         terminated pursuant to Section 4 or 5 of this Agreement; provided,
         however, that this Agreement shall automatically be renewed for
         successive one-year terms (the Term and, if the period of employment is
         so renewed, such additional period(s) of employment are collectively
         referred to herein as the "Term") unless terminated by written notice
         given by either party to the other at least 90 days prior to the end of
         the applicable Term."

         II.      This Amendment shall be governed by and construed and enforced
in accordance with the laws of the Commonwealth of Massachusetts applicable to
agreements made and to be performed entirely in Massachusetts.

         III.     Except as modified by this First Amendment, the Agreement
remains in full force and effect and unchanged.

                      [This space intentionally left blank]

                                       1
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                  IN WITNESS WHEREOF, the parties have executed this First
Amendment as of the date first written above.

                                         ARIAD PHARMACEUTICALS, INC.

                                         By: /s/ Harvey J. Berger
                                            -------------------------------
                                            Harvey J. Berger, M.D.
                                            Chairman and Chief Executive Officer

                                         EMPLOYEE

                                            /s/ Laurie A. Allen
                                         ----------------------------------
                                         Laurie A. Allen, Esq.

                                       2<PAGE>

                                                                    Exhibit 10.3

                     SIXTH AMENDMENT TO EMPLOYMENT AGREEMENT

         This AMENDMENT TO EMPLOYMENT AGREEMENT (the " Sixth Amendment") made as
of September 2, 2003 between ARIAD Pharmaceuticals, Inc., a Delaware corporation
(the "Company"), and David Berstein, Esq. (the "Employee").

         The Company and the Employee have entered into an Employment Agreement
dated as of August 1, 1993 as previously amended (the "Agreement"), and the
parties hereto desire to further amend certain provisions of the Agreement.

         NOW, THEREFORE, in consideration of the premises set forth herein and
for other good and valuable consideration, the receipt of which is hereby
acknowledged, the parties hereto agree to further amend the Agreement as
follows:

         I.       Term of Employment. The first sentence of Section 2 is hereby
amended to read as follows:

                  "The term of the Employee's employment under the Agreement is
         hereby extended to December 31, 2006 (the "Term"), unless sooner
         terminated pursuant to Section 4 or 5 of this Agreement; provided,
         however, that this Agreement shall automatically be renewed for
         successive one-year terms (the Term and, if the period of employment is
         so renewed, such additional period(s) of employment are collectively
         referred to herein as the "Term") unless terminated by written notice
         given by either party to the other at least 90 days prior to the end of
         the applicable Term."

         II.      This Amendment shall be governed by and construed and enforced
in accordance with the laws of the Commonwealth of Massachusetts applicable to
agreements made and to be performed entirely in Massachusetts.

         III.     Except as modified by this Sixth Amendment, the Agreement
remains in full force and effect and unchanged.

                      [This space intentionally left blank]

                                       1
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                  IN WITNESS WHEREOF, the parties have executed this Sixth
Amendment as of the date first written above.

                                         ARIAD PHARMACEUTICALS, INC.

                                         By: /s/ Harvey J. Berger
                                            -----------------------------
                                            Harvey J. Berger, M.D.
                                            Chairman and Chief Executive Officer

                                         EMPLOYEE

                                             /s/ David L. Berstein
                                         --------------------------------
                                         David Berstein, Esq.

                                       2<PAGE>

                                                                    Exhibit 10.4

                     THIRD AMENDMENT TO EMPLOYMENT AGREEMENT

         This AMENDMENT TO EMPLOYMENT AGREEMENT (the " Third Amendment") made as
of September 2, 2003, between ARIAD Pharmaceuticals, Inc., a Delaware
corporation (the "Company"), and Timothy P. Clackson, Ph.D. (the "Employee").

         The Company and the Employee have entered into an Employment Agreement
dated as of June 8, 2000 (the "Agreement"), as previously amended, and the
parties hereto desire to further amend certain provisions of the Agreement.

         NOW, THEREFORE, in consideration of the premises set forth herein and
for other good and valuable consideration, the receipt of which is hereby
acknowledged, the parties hereto agree to further amend the Agreement as
follows:

         I.       Term of Employment. The first sentence of Section 2 is hereby
amended to read as follows:

                  "The term of the Employee's employment under the Agreement is
         hereby extended to December 31, 2006 (the "Term"), unless sooner
         terminated pursuant to Section 4 or 5 of this Agreement; provided,
         however, that this Agreement shall automatically be renewed for
         successive one-year terms (the Term and, if the period of employment is
         so renewed, such additional period(s) of employment are collectively
         referred to herein as the "Term") unless terminated by written notice
         given by either party to the other at least 90 days prior to the end of
         the applicable Term."

         II.      This Amendment shall be governed by and construed and enforced
in accordance with the laws of the Commonwealth of Massachusetts applicable to
agreements made and to be performed entirely in Massachusetts.

         III.     Except as modified by this Third Amendment, the Agreement
remains in full force and effect and unchanged.

                      [This space intentionally left blank]

                                       1

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                  IN WITNESS WHEREOF, the parties have executed this Third
Amendment as of the date first written above.

                                         ARIAD PHARMACEUTICALS, INC.

                                         By: /s/ Harvey J. Berger
                                            ----------------------------
                                            Harvey J. Berger, M.D.
                                            Chairman and Chief Executive Officer

                                         EMPLOYEE

                                            /s/ Timothy P. Clackson
                                         --------------------------------
                                         Timothy P. Clackson, Ph.D.

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