EXHIBIT 10.11

                               GENZYME CORPORATION

                        1999 EMPLOYEE STOCK PURCHASE PLAN

1.   PURPOSE.

     The purpose of this 1999 Employee Stock Purchase Plan (the "Plan") is to
provide employees of Genzyme Corporation (the "Company") and its subsidiaries
who wish to become shareholders of the Company an opportunity to purchase shares
of the Company's common stock, $0.01 par value (the "Shares"). The Plan is
intended to qualify as an "employee stock purchase plan" within the meaning of
Section 423 of the Internal Revenue Code of 1986, as amended (the "Code").

     The Plan constitutes an amendment and restatement of the Company's 1990
Employee Stock Purchase Plan (the "1990 Plan"), which is hereby merged with and
into the Plan, and the separate existence of the 1990 Plan shall terminate on
the effective date of the Plan. The rights and privileges of the holders of
outstanding rights under the 1990 Plan shall not be adversely affected by the
foregoing action.

2.   ELIGIBLE EMPLOYEES.

     Subject to the provisions of Sections 7, 8 and 9 below, any individual who
is in the full-time employment (as defined below) of the Company, or any of its
subsidiaries (as defined in Section 425(f) of the Code), the employees of which
are designated by the Board of Directors as eligible to participate in the Plan,
is eligible to participate in any Offering of Shares (as defined in Section 3
below) made by the Company hereunder. Full-time employment shall include all
employees whose customary employment is:

     (a)  20 hours or more per week; and

     (b)  more than five months

in the calendar year during which said Offering Date (as defined in Section 3
below) occurs or in the calendar year immediately preceding such year.

3.   OFFERING DATES.

     From time to time, the Company, by action of the Board of Directors, will
grant rights to purchase the Shares to employees eligible to participate in the
Plan pursuant to one or more offerings (each of which is an "Offering") on a
date or series of dates (each of which is an "Offering Date") designated for
this purpose by the Board of Directors.

4.   PRICES.

     The price per share for each grant of rights hereunder shall be the lesser
of:

     (a)  eighty-five percent (85%) of the fair market value of a Share on the
Offering Date on which such right was granted; or

     (b)  eighty-five percent (85%) of the fair market value of a Share on the
date such right is exercised. At its discretion, the Board of Directors may
determine a higher price for a grant of rights.

                                        1


5.   EXERCISE OF RIGHTS AND METHOD OF PAYMENT.

     (a)  Rights granted under the Plan will be exercisable periodically on
specified dates as determined by the Board of Directors.

     (b)  The method of payment for Shares purchased upon exercise of rights
granted shall be through regular payroll deductions or by lump sum cash payment
or both, as determined by the Board of Directors. No interest shall be paid upon
payroll deductions unless specifically provided for by the Board of Directors.

     (c)  Any payments received by the Company from a participating employee and
not utilized for the purchase of Shares upon exercise of a right granted
hereunder shall be promptly returned to such employee by the Company after
termination of the right to which the payment relates.

6.   TERM OF RIGHTS.

     The total period from an Offering Date to the last date on which rights
granted on that Offering Date are exercisable (the "Offering Period") shall in
no event be longer than twenty-seven (27) months. The Board of Directors when it
authorizes an Offering may designate one or more exercise periods during the
Offering Period. Rights granted on an Offering Date shall be exercisable in full
on the Offering Date or in such proportion on the last day of each exercise
period as the Board of Directors determines.

7.   SHARES SUBJECT TO THE PLAN.

     The aggregate number of shares that may be issued upon exercise of options
granted under this Plan is 5,829,391. Appropriate adjustments in the number of
Shares subject to the Plan, in the number of Shares covered by outstanding
rights granted hereunder, in the exercise price of the rights and in the maximum
number of Shares which an employee may purchase (pursuant to Section 8 below)
shall be made to give effect to any mergers, consolidations, reorganizations,
recapitalizations, stock splits, stock dividends or other relevant changes in
the capitalization of the Company occurring after the effective date of the
Plan, provided that no fractional Shares shall be subject to a right and each
right shall be adjusted downward to the nearest full Share. Any agreement of
merger or consolidation shall include provisions for protection of the then
existing rights of participating employees under the Plan. Either authorized and
unissued Shares or issued Shares heretofore or hereafter reacquired by the
Company may be subject to rights under the Plan. If for any reason any right
under the Plan terminates in whole or in part, Shares subject to such terminated
right may be subject to a right under the Plan.

8.   LIMITATIONS ON GRANTS.

     (a)  No employee shall be granted a right hereunder if such employee,
immediately after the right is granted would own stock or rights to purchase
stock possessing five percent (5%) or more of the total combined voting power or
value of all series of common stock of the Company, or of any subsidiary,
computed in accordance with Section 423(b)(3) of the Code.

     (b)  No employee shall be granted a right which permits the employee's
rights to purchase shares under all employee stock purchase plans of the Company
and its subsidiaries to accrue at a rate which exceeds twenty-five thousand
dollars ($25,000) (or such other maximum as may be prescribed from time to time
by the Code) of the fair market value of such shares (determined at the time
such right is granted) for each calendar year in which such right is outstanding
at any time in accordance with the provisions of Section 423(b)(8) of the Code.

                                        2


     (c)  No right granted to any participating employee under an Offering, when
aggregated with rights granted under any other Offering still exercisable by the
participating employee, shall cover more shares than may be purchased at an
exercise price not to exceed fifteen percent (15%) of the employee's annual rate
of compensation on the date the employee elects to participate in the Offering
or such lesser percentage as the Board of Directors may determine.

9.   LIMIT ON PARTICIPATION.

     Participation in an Offering shall be limited to eligible employees who
elect to participate in such Offering in the manner, and within the time
limitations, established by the Board of Directors when it authorizes the
Offering.

10.  CANCELLATION OF ELECTION TO PARTICIPATE.

     An employee who has elected to participate in an Offering may cancel such
election as to all (but not part) of the unexercised rights granted under such
Offering by giving written notice of such cancellation to the Company before the
expiration of any exercise period. Any amounts paid by the employee for the
Shares or withheld for the purchase of Shares from the employee's compensation
through payroll deductions shall be paid to the employee, without interest
unless otherwise determined by the Board of Directors, upon such cancellation.

11.  TERMINATION OF EMPLOYMENT.

     Upon the termination of employment for any reason, including the death of
the employee, before the date on which any rights granted under the Plan are
exercisable, all such rights shall immediately terminate and amounts paid by the
employee for the Shares or withheld for the purchase of Shares from the
employee's compensation through payroll deductions shall be paid to the employee
or to the employee's estate, without interest unless otherwise determined by the
Board of Directors.

12.  EMPLOYEE'S RIGHTS AS SHAREHOLDER.

     No participating employee shall have any rights as a shareholder in the
Shares covered by a right granted hereunder until such right has been exercised,
full payment has been made for the corresponding Share and the Share certificate
is actually issued.

13.  RIGHTS NOT TRANSFERABLE.

     Rights under the Plan are not assignable or transferable by a participating
employee and are exercisable only by the employee.

14.  AMENDMENTS TO OR DISCONTINUATION OF THE PLAN.

     The Board of Directors of the Company shall have the right to amend, modify
or terminate the Plan at any time without notice; provided, however, that the
then existing rights of all participating employees shall not be adversely
affected thereby, and provided further that, subject to the provisions of
Section 7 above, no such amendment to the Plan shall, without the approval of
the shareholders of the Company, increase the total number of Shares which may
be offered under the Plan.

15.  EFFECTIVE DATE AND APPROVALS.

     Subject to the approval of the shareholders of the Company, this Plan shall
be effective on March 24, 1999, the date it was adopted by the Board of
Directors.

                                        3


     The Company's obligation to offer, sell and deliver its Shares under the
Plan is subject to (i) the approval of any governmental authority required in
connection with the authorization, issuance or sale of such Shares, (ii)
satisfaction of the listing requirements of any national securities exchange on
which the Shares are then listed and (iii) compliance, in the opinion of the
Company's counsel, with all applicable federal and state securities and other
laws.

16.  TERM OF PLAN.

     No rights shall be granted under the Plan after March 24, 2009.

17.  ADMINISTRATION OF THE PLAN.

     The Board of Directors or any committee or person(s) to whom it delegates
its authority (the "Administrator") shall administer, interpret and apply all
provisions of the Plan as it deems necessary. Nothing contained in this Section
shall be deemed to authorize the Administrator to alter or administer the
provisions of the Plan in a manner inconsistent with the provisions of Section
423 of the Code.

18.  RIGHTS LIMITED.

     In no event shall the Plan form a part of an employee's contract of
employment or service, if any. The Plan shall not confer upon any employee of
the Company or its subsidiaries any right with respect to the continuance of his
or her employment by, or other service with, the Company or its subsidiary, nor
shall it limit the right of the Company or its subsidiaries to terminate the
employee or otherwise change the terms of employment. The loss of existing or
potential profit in any Offering of Shares shall not constitute an element of
damages in the event of termination of employment for any reason, even if the
termination is in violation of an obligation of the Company or its subsidiary to
the employee.

                                        4