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                                                                    EXHIBIT 10.4

                               GENZYME CORPORATION

                           1997 EQUITY INCENTIVE PLAN

1.   PURPOSE

          The purpose of the Genzyme Corporation 1997 Equity Incentive Plan (the
"Plan") is to attract and retain key employees and consultants of the Company
and its Affiliates, to provide an incentive for them to achieve long-range
performance goals, and to enable them to participate in the long-term growth of
the Company by granting them Awards with respect to the Company's Common Stock.
Certain capitalized terms used herein are defined in section 9 below.

2.   ADMINISTRATION

          The Plan shall be administered by the Committee. The Committee shall
determine the terms and conditions of the Awards. The Committee shall have
authority to adopt, alter and repeal such administrative rules, guidelines and
practices governing the operation of the Plan as it shall from time to time
consider advisable, and to interpret the provisions of the Plan. The Committee's
decisions shall be final and binding. To the extent permitted by applicable law,
the Committee may delegate to one or more executive officers of the Company the
power to make Awards to Participants and all determinations under the Plan with
respect thereto, provided that the Committee shall fix the maximum amount of
such Awards for all such Participants and a maximum for any one Participant.

3.   ELIGIBILITY

          All employees and consultants of the Company or any Affiliate capable
of contributing significantly to the successful performance of the Company are
eligible to be Participants in the Plan, other than persons deemed to be
officers or directors of the Company within the meaning of the corporate
governance rules for Nasdaq National Market companies. The Committee, in its
sole discretion, shall determine from the group of eligible persons whether an
individual shall be a Participant under the Plan."

4.   STOCK AVAILABLE FOR AWARDS

(a)  AMOUNT. Subject to adjustment under subsection (b), Awards may be made
under the Plan for up to 27,664,300 shares of Genzyme General Stock. If any
Award expires or is terminated unexercised or is forfeited or settled in a
manner that results in fewer shares outstanding than were awarded, the shares
subject to such Award, to the extent of such expiration, termination, forfeiture
or decrease, shall again be available for award under the Plan. Common Stock
issued through the assumption or substitution of outstanding grants from an
acquired company shall not reduce the shares available for Awards under the
Plan. Shares issued under the Plan may consist in whole or in part of authorized
but unissued shares or treasury shares.

(b)  ADJUSTMENT. In the event that the Committee determines that any stock
dividend, extraordinary cash dividend, recapitalization, reorganization, merger,
consolidation, split-up, spin-off, combination, exchange of shares or other
transaction affects the Common Stock such that an adjustment is required in
order to preserve the benefits intended to be provided by the Plan, then the
Committee shall equitably adjust any or all of (i) the number and kind of shares
in respect of which Awards may be made under the Plan, (ii) the number and kind
of shares subject to outstanding Awards and (iii) the exercise price with
respect to any of the foregoing, provided that the number of shares subject to
any Award shall always be a whole number, and if considered appropriate, the
Committee may make provision for a cash payment with respect to an outstanding
Award. Notwithstanding the foregoing, unless otherwise determined by the
Committee, no

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adjustment will be made for dividends of one series of Common Stock paid on
another series of Common Stock.

5.   STOCK OPTIONS

(a)  GRANT OF OPTIONS. Subject to the provisions of the Plan, the Committee may
grant Options to purchase shares of Common Stock. The Committee shall determine
the number of shares subject to each Option and the exercise price therefor,
which shall not be less than 100% of the Fair Market Value of the Common Stock
as of the Pricing Date. The Plan does not provide for the granting of incentive
stock options meeting the requirements of Section 422 of the Code.

(b)  TERMS AND CONDITIONS. Each Option shall be exercisable at such times and
subject to such terms and conditions as the Committee may specify in the
applicable grant or thereafter. The Committee may impose such conditions with
respect to the exercise of Options, including conditions relating to applicable
federal or state securities laws, as it considers necessary or advisable.

(c)  PAYMENT. No shares shall be delivered pursuant to any exercise of an Option
until payment in full of the exercise price therefor is received by the Company.
Such payment may be made in whole or in part in cash or, to the extent permitted
by the Committee at or after the grant of the Option, by delivery of a note or
other commitment satisfactory to the Committee or shares of Common Stock owned
by the optionee, including Restricted Stock, or by retaining shares otherwise
issuable pursuant to the Option, in each case valued at their Fair Market Value
on the date of delivery or retention, or such other lawful consideration,
including a payment commitment of a financial or brokerage institution, as the
Committee may determine.

6.   GENERAL PROVISIONS APPLICABLE TO AWARDS

(a)  DOCUMENTATION. Each Award under the Plan shall be evidenced by a writing
delivered to the Participant specifying the terms and conditions thereof and
containing such other terms and conditions not inconsistent with the provisions
of the Plan as the Committee considers necessary or advisable to achieve the
purposes of the Plan or to comply with applicable tax and regulatory laws and
accounting principles.

(b)  COMMITTEE DISCRETION. The terms of each Award need not be identical, and
the Committee need not treat Participants uniformly. Except as otherwise
provided by the Plan or a particular Award, any determination with respect to an
Award may be made by the Committee at the time of grant or at any time
thereafter.

(c)  DIVIDENDS AND CASH AWARDS. In the discretion of the Committee, any Award
under the Plan may provide the Participant with (i) dividends or dividend
equivalents payable (in cash or in the form of Awards under the Plan) currently
or deferred with or without interest and (ii) cash payments in lieu of or in
addition to an Award.

(d)  TERMINATION OF EMPLOYMENT. The Committee shall determine the effect on an
Award of the disability, death, retirement or other termination of employment of
a Participant and the extent to which, and the period during which, the
Participant's legal representative, guardian or Designated Beneficiary may
receive payment of an Award or exercise rights thereunder.

(e)  CHANGE IN CONTROL. In order to preserve a Participant's rights under an
Award in the event of a change in control of the Company (as defined by the
Committee), the Committee in its discretion may, at the time an Award is made or
at any time thereafter, take one or more of the following actions: (i) provide
for the acceleration of any time period relating to the exercise or payment of
the Award, (ii) provide for payment to the Participant of cash or other property
with a Fair Market Value equal to the amount that would have been received upon
the exercise or payment of the Award had the Award been exercised or paid upon
the change in control, (iii) adjust the terms of the Award in a manner
determined by the Committee to reflect the change in control, (iv) cause the
Award to be assumed, or new rights substituted therefor, by

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another entity, or (v) make such other provision as the Committee may consider
equitable to Participants and in the best interests of the Company.

(f)  TRANSFERABILITY. In the discretion of the Committee, any Award may be made
transferable upon such terms and conditions and to such extent as the Committee
determines. The Committee may in its discretion waive any restriction on
transferability.

(g)  LOANS. The Committee may authorize the making of loans or cash payments to
Participants in connection with the grant or exercise of any Award under the
Plan, which loans may be secured by any security, including Common Stock,
underlying or related to such Award (provided that the loan shall not exceed the
Fair Market Value of the security subject to such Award), and which may be
forgiven upon such terms and conditions as the Committee may establish at the
time of such loan or at any time thereafter.

(h)  WITHHOLDING TAXES. The Participant shall pay to the Company, or make
provision satisfactory to the Committee for payment of, any taxes required by
law to be withheld in respect of Awards under the Plan no later than the date of
the event creating the tax liability. The Company and its Affiliates may, to the
extent permitted by law, deduct any such tax obligations from any payment of any
kind otherwise due to the Participant. In the Committee's discretion, such tax
obligations may be paid in whole or in part in shares of Common Stock, including
shares retained from the Award creating the tax obligation, valued at their Fair
Market Value on the date of delivery.

(i)  FOREIGN NATIONALS. Awards may be made to Participants who are foreign
nationals or employed outside the United States on such terms and conditions
different from those specified in the Plan as the Committee considers necessary
or advisable to achieve the purposes of the Plan or to comply with applicable
laws.

(j)  AMENDMENT OF AWARD. The Committee may amend, modify or terminate any
outstanding Award, including substituting therefor another Award of the same or
a different type, changing the date of exercise or realization, provided that
the Participant's consent to such action shall be required unless the Committee
determines that the action, taking into account any related action, would not
materially and adversely affect the Participant.

7.   CERTAIN DEFINITIONS

          "Affiliate" means any business entity in which the Company owns
directly or indirectly 50% or more of the total voting power or has a
significant financial interest as determined by the Committee.

          "Award" means any Stock Option granted under the Plan.

          "Board" means the Board of Directors of the Company.

          "Code" means the Internal Revenue Code of 1986, as amended from time
to time, or any successor law.

          "Committee" means one or more committees each comprised of not less
than two members of the Board appointed by the Board to administer the Plan or a
specified portion thereof.

          "Common Stock" or "Stock" means the common stock, $.01 par value, of
the Company.

          "Company" means Genzyme Corporation.

          "Designated Beneficiary" means the beneficiary designated by a
Participant, in a manner determined by the Committee, to receive amounts due or
exercise rights of the Participant in the event of the Participant's death. In
the absence of an effective designation by a Participant, "Designated
Beneficiary" means the Participant's estate.

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          "Fair Market Value" means, with respect to Common Stock or any other
property, the fair market value of such property as determined by the Committee
in good faith or in the manner established by the Committee from time to time.

          "Participant" means a person selected by the Committee to receive an
Award under the Plan.

          "Pricing Date" means the date on which the Award is granted, except
that the Committee may provide that the Pricing Date for an Award granted to a
new employee or consultant shall be the date on which the recipient is hired or
engaged if the grant of the Award occurs within 90 days of the date such
employment or engagement commences.

          "Stock Option" or "Option" means an option to purchase shares of
Common Stock awarded to a Participant under Section 5.

8.   MISCELLANEOUS

(a)  RIGHTS LIMITED. Any Award made under the Plan shall be made in the sole
discretion of the Committee, or its delegate as appointed in accordance with the
Plan, and no prior Award shall entitle a person to any future Award. In no event
shall the Plan, or any Award made under the Plan, form a part of an employee's
or consultant's contract of employment or service, if any. Neither the Plan, nor
any Award made under the Plan, shall confer upon any employee or consultant of
the Company or its Affiliate any right with respect to the continuance of his or
her employment by, or other service with, the Company or its Affiliate, nor
shall they limit the right of the Company or its Affiliate to terminate the
employee or consultant or otherwise change the terms of service. The loss of
existing or potential profit in an Award shall not constitute an element of
damages in the event of termination of employment or service for any reason,
even if the termination is in violation of an obligation of the Company or its
Affiliate to the Participant.

(b)  NO RIGHTS AS STOCKHOLDER. Subject to the provisions of the applicable
Award, no Participant or Designated Beneficiary shall have any rights as a
stockholder with respect to any shares of Common Stock to be distributed under
the Plan until he or she becomes the holder thereof. A Participant to whom
Common Stock is awarded shall be considered the holder of the Stock at the time
of the Award except as otherwise provided in the applicable Award.

(c)  EFFECTIVE DATE. The Plan shall be effective on October 16, 1997.

(d)  AMENDMENT OF PLAN. The Board may amend, suspend or terminate the Plan or
any portion thereof at any time.

(e)  GOVERNING LAW. The provisions of the Plan shall be governed by and
interpreted in accordance with the laws of Massachusetts.

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