Exhibit 10.18

Millennium Pharmaceuticals, Inc.
Description of Non-Employee Director Compensation

We do not pay directors who are also Millennium employees any additional compensation for their service as a director. We do pay our non-employee
directors for their service as directors.

Each
year, the Board Governance Committee reviews the compensation we pay to our non-employee directors. The Committee compares our Board compensation to compensation paid to
non-employee directors by similarly sized public companies in similar businesses. The Committee also considers the responsibilities that we ask our Board members to assume and the amount
of time required to perform those responsibilities.

Below
we show the rate of compensation that we pay to our non-employee directors effective January 1, 2005.

Cash Compensation

Each director who is not an employee of Millennium receives:

|Type of Fee                                           |  | Amount |        | For each
|----------------------------------------------------- |  | ------ | ------ | --------
|Annual retainer:                                      |  | $      | 25,000 |         
|Additional annual retainer for lead outside director: |  | $      | 10,000 |         
|Attendance:                                           |  | $      | 2,000  |         
|                                                      |  | $      | 1,000  |         
|                                                      |  | $      | 1,000  |         
|                                                      |  | $      | 750    |         

Millennium
also reimburses non-employee directors for reasonable travel and out-of-pocket expenses incurred in connection with their service as
directors.

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Stock Compensation

Directors also participate in our 2000 Stock Incentive Plan. Under the option program for directors adopted by the Board, our non-employee directors
receive stock option grants as follows:

|                       |  | Number
of shares |  | Granted in three
installments on                                                                     |  | Vesting
Schedule                                                                                                                               
|---------------------- |  | ---------------- |  | ---------------------------------------------------------------------------------------------------- |  | -----------------------------------------------------------------------------------------------------------------------------------------------
|Initial Option Grant:  |  | 35,000           |  | the date the director is first elected, one month later and two months later                         |  | vest on a monthly basis beginning one month from the date of election and become fully vested on the fourth anniversary of the date of election
|Annual Option Grant:   |  | 15,000           |  | May 1st, June 1st and July 1st of each year, prorated for service on the Board of less than one year |  | vest on a monthly basis beginning as of June 1st in the year granted and become fully vested on May 1st of the fourth year after the grant date
|Committee Chair:       |  | 500              |  | the dates of the annual option grant                                                                 |  | same as annual grant                                                                                                                           
|Lead Outside Director: |  | 5,000            |  | the dates of the annual option grant                                                                 |  | same as annual grant                                                                                                                           

Each
option terminates on the earlier of ten years after the date of grant or the date 90 days after the option holder ceases to serve as a director or employee (or one year in
the case of disability and three years in the event of death).

Under
the 2000 Plan, an option becomes fully vested in the event of the death of the director. The exercise price of options granted under the 2000 Plan is equal to the closing price of
Millennium common stock as quoted on the NASDAQ stock market on the date of grant.

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