Exhibit 10.1

Millennium Pharmaceuticals, Inc.

DESCRIPTION OF SUCCESS SHARING BONUS PROGRAM

        Millennium Pharmaceuticals, Inc. (the “Company”) maintains a Success
Sharing Bonus Program for all employees including the Company’s executive
officers. Through this program, employees can receive an annual cash bonus based
on achievement of key Company and individual goals.  There is no guarantee that
a bonus pool will be available in any given year, or that every employee will
receive a bonus. The plan is intended to strengthen the link between individual
compensation and Company success; reinforce the Company’s pay-for-performance
philosophy by delivering higher bonuses to higher performing employees; and help
ensure that the Company’s cash compensation is competitive.

        The amount of bonus dollars available in the pool is tied directly to
the Company’s performance against priority goals.  These priority goals are set
each year by the Company’s Compensation and Talent Committee (the “Committee”)
and Board of Directors. The priority goals typically address product sales;
product/pipeline development; organizational development; and finance/value
creation.

        After the end of each year, the Committee makes a funding determination
based on its assessment of the Company’s overall achievements related to these
priority goals. Fifty percent or more of the success sharing pool is available
if a threshold of performance is reached and 100% if goals are achieved. The
maximum payable under the program is 150%. Individual bonuses are based on
individual employee performance as assessed in the performance review process
and the target bonus percent for the position.  Individual bonuses can vary
significantly based on performance. Bonuses for any particular year are paid as
a lump sum cash award in March of the following year.

        Executive officers (including the Chief Executive Officer) are eligible
to receive bonuses under the program of between zero and 50% of base salary. The
target bonus amount for the Company’s executive officers is between 35% and 50%
of base salary.