<Page>

                                                                 EXHIBIT 10.25

Millennium Pharmaceuticals, Inc. has entered into an employment offer letter
on substantially the terms set forth in the attached employment offer letter
with each of the below-named executive officers of Millennium, on the dates
indicated:


NAME OF EXECUTIVE OFFICER             DATE OF EXECUTION
-------------------------             -----------------

John B. Douglas III                   April 28, 1999
Linda K. Pine                         September 27, 1994
Robert I. Tepper, M.D.                May 5, 1994




<Page>


DATE

NAME
ADDRESS

Dear

On behalf of Millennium Pharmaceuticals, Inc. (the "Company"), I am pleased
to offer you the position of XXXX reporting to XXXX.

1. JOB RESPONSIBILITIES: Your job responsibilities in this position will
   include the following:

   Your short-term goals will include:

   Your long-term goals will include:

/  / Actively participate in recruiting an outstanding scientific and management
   team for Millennium.

/  / Creating and supporting an environment in the Company that is highly
   motivating, creative, goal-oriented and a place where all business people and
   scientists want to work.

2. EFFECTIVE DATE: The effective date of your full-time employment with the
   Company is to be determined upon your formal acceptance of this offer.

3. SALARY: Your base salary will initially be XXXX per annum. Your salary will
   be paid periodically in accordance with the Company's payroll procedures. In
   addition, in accordance with the Company's compensation practices, you will
   receive, approximately annually, a salary review which will be based on your
   performance, the Company's performance and such other factors as may be
   determined by the Company's Board of Directors.

4. BENEFITS: You and your dependents will be eligible for the Company's standard
   medical, dental, life insurance, disability benefits and Section 125
   cafeteria plan. After the standard waiting periods, you will also be eligible
   to participate in the Company's 401(k) and Employee Stock Purchase plans. You
   will accrue vacation at the rate of 1.25 days per month of full-time
   employment. Standard paid holidays will be observed. Transportation benefits,
   including a choice of MBTA pass up to $60 or contributory off-site parking,
   are also available. The Company, however, reserves the right to modify its
   employee benefit programs from time-to-time.

<Page>

5. EQUITY PARTICIPATION, VESTING OF STOCK: Subject to approval by the Company's
   Board of Directors, you will be granted an incentive stock option exercisable
   for XXXX shares of the Company's Common Stock at an exercise price equal to
   the current fair market value of the Company's Common Stock as determined by
   the Company's Board of Directors. This option will vest as to one fourth
   (1/4) of the shares on the first anniversary of your commencement of
   full-time employment with the Company and as to one forty-eighth (1/48) of
   the shares at the end of each full month thereafter until all shares are
   vested, provided that you remain employed by the Company. In the event of
   your death or total and permanent disability (as defined in the Internal
   Revenue Code of 1986, as amended) during the first year of your employment,
   the initial one-fourth (1/4) of your shares that would have vested at the end
   of your first year of employment shall vest. In the event of termination of
   your employment for any reason (except as set forth in the preceding
   sentence), vesting shall cease. Please refer to the Company's Incentive Stock
   Plan for complete details.

   In addition, subject to the approval of the respective Boards of Directors of
   each Millennium subsidiary, you will be granted stock options of 3,000 shares
   in each subsidiary under the terms of the Millennium Intercompany Stock
   Program. These options will each vest as to one forty-eighth (1/48) of the
   shares monthly.

6. EMPLOYMENT PERIOD: Your employment with the Company will be at-will, meaning
   that you will not be obligated to remain employed by the Company for any
   specified period of time; likewise, the Company will not be obligated to
   continue your employment for any specific period and may terminate your
   employment at any time, with or without cause.

7. SEVERANCE: In the event that your employment is terminated by the Company
   other than for Justifiable Cause (as defined below, the Company will pay you
   a severance payment (the "Severance Payment") equal to 12 months' salary (no
   stock vesting). The Severance Payment will be payable periodically in
   accordance with the Company's payroll procedures as then in effect and the
   Company's obligation to make the Severance Payment will cease in the event
   that you accept other employment. In the event your employment is terminated
   by the Company for Justifiable Cause (as defined below) or voluntarily by
   you, you will not be entitled to any Severance Payment.

   For purposes hereof, the term "Justifiable Cause" shall mean the occurrence
   of any of the following events: (i) your conviction of, or pleas of nolo
   contendere with respect to a felony or a crime involving moral turpitude,
   (ii) your commission of an act of personal dishonesty or breach of fiduciary
   duty involving personal profit in connection with the Company, (iii) your
   commission of an act, or failure to act, which the Board of Directors of the
   Company shall reasonably have found to have involved willful misconduct or
   gross negligence on your part, in the conduct of your duties hereunder, (iv)
   habitual absenteeism, alcoholism or drug dependence on your part which
   interferes with the performance of your duties hereunder, (v) your willful
   and

<Page>

   material breach or refusal to perform your services as provided herein,
   (vi) any other material breach by you of the provisions hereof or (vii) your
   willful and material failure or refusal to carry out a direct request of the
   Board of Directors or Chief Executive Officer. In the event that the Company
   terminates your employment for Justifiable Cause, the Company will provide
   you with a statement of the basis for such termination and an opportunity to
   respond thereto.

8. EMPLOYMENT ELIGIBILITY VERIFICATION: Please note that all persons employed in
   the United States, are required to complete an Employment Eligibility
   Verification Form on the first day of employment and submit an original
   document or documents that establish identity and employment eligibility
   within three business days of employment. For your convenience, we are
   enclosing Form I-9 for your review. You will need to complete Section 1 and
   present original document(s) of your choice as listed on the reverse side of
   the form once you begin work.

9. PROPRIETARY INFORMATION, NO CONFLICTS: You agree to execute the Company's
   standard form of Invention, Non-Disclosure and Non-Competition Agreement and
   to be bound by all of the provisions thereof. You hereby represent that you
   are not presently bound by any employment agreement, confidential or
   proprietary information agreement or similar agreement with any current or
   previous employer that would impose any restriction on your acceptance of
   this offer or that would interfere with your ability to fulfill the
   responsibilities of your position with the Company.

10.MEDICAL SURVEILLANCE: As part of Millennium's medical surveillance program,
   employees are required to have an initial physical, provided at Mt. Auburn
   Hospital. All laboratory employees working with hazardous chemical,
   infectious agents, radio labeled materials or animals shall have access to
   medical attention, including initial and periodic medical exams without cost
   to the employee or loss of pay. An employee may refuse an exam if he/she
   signs a release. If you want to decline from having the initial physical,
   please notify Human Resources on your first day at New Employee Orientation.
   Your initial surveillance examination will be scheduled to take place during
   the first week of your employment.

11.NEW EMPLOYEE ORIENTATION: On the first Monday of your employment with
   the Company, you should arrive at our 75 Sidney Street location for New
   Employee Orientation.

12.SIGN-ON BONUS: The Company will pay you a bonus of XXXX. Payment will be
   made on the date of the first paycheck following commencement of your full
   time employment. Should you terminate for any reason within 12 months of your
   starting date after having received your bonus, the Company reserves the
   right to seek repayment of all or a pro-rata portion of your bonus.


<Page>




13.RELOCATION EXPENSES: Upon your acceptance of this offer, you are eligible
   for reimbursement of the following expenses associated with your relocation:

         XXXX

XXXX, all of us here at Millennium are very enthusiastic about your commitment
to joining the Company and have the highest expectation of your future
contributions.

Please indicate your acceptance of the foregoing by signing the enclosed copy of
this letter and returning it to the Company no later than XXXX. After that date,
the offer will lapse.

Very truly yours,
MILLENNIUM PHARMACEUTICALS, INC.

Linda K. Pine
Sr. Vice President, Human Resources

The foregoing is signed and accepted as of the date first above written by:

-------------                              ------------
XXXXXX                                            Date