EXHIBIT 10.51


                               FINANCIAL COVENANTS
                                ADDENDUM NO. 001
                            TO MASTER LEASE AGREEMENT

                          DATED AS OF DECEMBER 27, 2001


THIS ADDENDUM (this "Addendum") amends and supplements the above referenced
agreement (the "Agreement"), between General Electric Capital Corporation
(together with its successors and assigns, if any, "Lender") and Ariad
Pharmaceuticals, Inc. (each of the aforementioned parties shall hereinafter be
collectively referred to as "Borrower") and is hereby incorporated into the
Agreement as though fully set forth therein. Capitalized terms not otherwise
defined herein shall have the meanings set forth in the Lease.

The Agreement is hereby amended by adding the following:

FINANCIAL COVENANTS.

(a)    Borrower shall, at all times during the term of the Agreement, comply
       with the following:

       Maintain minimum Unrestricted Cash (as defined below) in the amount of
       $10,000,000.00. If this covenant is violated, Borrower will provide
       Lender within ten (10) days of such occurrence, an irrevocable letter of
       credit as described in section (c) below.

       Unrestricted Cash shall be defined as cash on hand, including investments
       in marketable securities with maturities of less than twenty four (24)
       months, less cash pledged to other parties and any contingent liability
       associated with similar cash covenants under leases, loans or other
       financial arrangements.

(b)    COMPLIANCE REPORTS. Borrower's Authorized Representative shall certify
       that Borrower is in compliance with the requirements of subsection (a)
       above. Such notification and certification shall be provided within
       ninety (90) days after the end of each fiscal year, the "Compliance
       Date"), reflecting such information as of the end of such fiscal year. If
       Borrower fails timely to provide such notification and compliance
       certificates, within fifteen (15) days after the Compliance Date, such
       failure shall automatically be deemed a default under the Agreement
       without notice or other act by Lender. The reports required under this
       section are in addition to and not a substitute for the reports required
       under the REPORTS Section of the Agreement.

(c)    The irrevocable letter of credit provided pursuant to this addendum under
       a default of Financial Covenant shall be (i) in an amount equal to the
       total of all Borrower's then outstanding Indebtedness to Lender under
       this Agreement, (ii) issued by a bank which is acceptable to Lender in
       its sole discretion, (iii) in the form attached as Exhibit A or as may be
       acceptable to Lender in its sole discretion, and (iv) for an initial term
       of at least one (1) year with automatic renewals thereafter (without
       amendment except for extension of the then current expiration date by an
       additional year) until Borrower has received written notice from Lender
       to the effect that the letter of credit is being released in its
       entirety. Borrower shall also execute a Letter of Credit Agreement in the
       form attached as Exhibit B.

Except as expressly modified hereby, all terms and provisions of the Lease shall
remain in full force and effect. This Addendum is not binding nor effective with
respect to the Lease until executed on behalf of Lender and Borrower by
authorized representatives of Lender and Borrower.


IN WITNESS WHEREOF, Borrower and Lender have caused this Addendum to be executed
by their duly authorized representatives as of the date first above written.


LENDER:                               BORROWER:


GENERAL ELECTRIC CAPITAL CORPORATION  ARIAD PHARMACEUTICALS, INC.


By: /s/ John Edel                     By: /s/ Brian A. Lajoie
    ---------------------------           --------------------------------------
    Name: JOHN EDEL                       Name:  BRIAN A. LAJOIE
    Title: SVP                            Title: Interim Chief Financial Officer



                                      ATTEST

                                      By: /s/ Joseph Bratica
                                          --------------------------------------
                                          Name: Joseph Bratica