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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

AMENDMENT NO. 1
to
FORM 10-K
Annual Report Pursuant to Section 13 or 15(d)
of the Securities Exchange Act of 1934

For the fiscal year ended December 31, 2002

Commission File No. 0-14680

GENZYME CORPORATION
(Exact name of registrant as specified in its charter)

Massachusetts (State or other jurisdiction of incorporation or organization)	06-1047163 (I.R.S. Employer Identification No.)
One Kendall Square Cambridge, Massachusetts (Address of principal executive office)	02139 (Zip Code)

(617) 252-7500
(Registrant's telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:
None

Securities registered pursuant to Section 12(g) of the Act:
Genzyme General Division Common Stock, $0.01 Par Value ("Genzyme General Stock")
Genzyme Biosurgery Division Common Stock, $0.01 Par Value ("Biosurgery Stock")
Genzyme Molecular Oncology Division Common Stock, $0.01 Par Value ("Molecular Oncology Stock")
Genzyme General Stock Purchase Rights
Biosurgery Stock Purchase Rights
Molecular Oncology Stock Purchase Rights

        Indicate by check mark whether the Registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Act of 1934 during the preceding 12 months (or for such shorter period that the Registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    YES ý    NO o

        Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of Registrant's knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. o

        Indicate by check mark whether the Registrant is an accelerated filer (as defined in the Exchange Act Rule 12b-2).    YES ý    NO o

        Aggregate market value of voting stock held by non-affiliates of the Registrant as of June 28, 2002: $4,320,206,618

        Number of shares of Genzyme General Stock outstanding as of March 1, 2003: 215,119,078

        Number of shares of Biosurgery Stock outstanding as of March 1, 2003: 40,583,935

        Number of shares of Molecular Oncology Stock outstanding as of March 1, 2003: 16,940,769

DOCUMENTS INCORPORATED BY REFERENCE

        Portions of the 2002 Genzyme General, Genzyme Biosurgery and Genzyme Molecular Oncology Annual Reports are incorporated by reference into Parts I, II and IV of this Form 10-K. Portions of the Registrant's Proxy Statement for the Annual Meeting of Stockholders to be held on May 29, 2003 are incorporated by reference into Part III of this Form 10-K.

EXPLANATORY NOTE

        We are filing this amendment to our Annual Report on Form 10-K for the year ended December 31, 2002 (our 2002 10-K), originally filed with the Securities and Exchange Commission on March 31, 2003, solely for the purpose of including the certifications of our chief executive officer and chief financial officer as required by Rule 13a-14 of the Securities Exchange Act of 1934. These certifications were omitted from the original filing of our 2002 10-K due to a technical error by our EDGAR filing agent.

        This amendment does not amend any information previously filed in our 2002 10-K.

SIGNATURE

        Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

	GENZYME CORPORATION
DATED: April 29, 2003	By:	/s/  MICHAEL S. WYZGA Michael S. Wyzga Senior Vice President, Finance, Chief Financial Officer, and Chief Accounting Officer

CERTIFICATION

I, Henri A. Termeer, certify that:

1.

I have reviewed this annual report on Form 10-K of Genzyme Corporation (the "Registrant");



2.

Based on my knowledge, this annual report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this annual report;



3.

Based on my knowledge, the financial statements, and other financial information included in this annual report, fairly present in all material respects the financial condition, results of operations and cash flows of the Registrant as of, and for, the periods presented in this annual report;



4.

The Registrant's other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-14 and 15d-14) for the Registrant and we have:



a)

designed such disclosure controls and procedures to ensure that material information relating to the Registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this annual report is being prepared;



b)

evaluated the effectiveness of the Registrant's disclosure controls and procedures as of a date within 90 days prior to the filing date of this annual report (the "Evaluation Date"); and



c)

presented in this annual report our conclusions about the effectiveness of the disclosure controls and procedures based on our evaluation as of the Evaluation Date;




5.

The Registrant's other certifying officer and I have disclosed, based on our most recent evaluation, to the Registrant's auditors and the audit committee of Registrant's board of directors (or persons performing the equivalent function):



a)

all significant deficiencies in the design or operation of internal controls which could adversely affect the Registrant's ability to record, process, summarize and report financial data and have identified for the Registrant's auditors any material weaknesses in internal controls; and



b)

any fraud, whether or not material, that involves management or other employees who have a significant role in the Registrant's internal controls; and




6.

The Registrant's other certifying officer and I have indicated in this annual report whether or not there were significant changes in internal controls or in other factors that could significantly affect internal controls subsequent to the date of our most recent evaluation, including any corrective actions with regard to significant deficiencies and material weaknesses.

Date: March 28, 2003 /s/  HENRI A. TERMEER Henri A. Termeer
Chief Executive Officer

CERTIFICATION

I, Michael S. Wyzga, certify that:

1.

I have reviewed this annual report on Form 10-K of Genzyme Corporation (the "Registrant");



2.

Based on my knowledge, this annual report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this annual report;



3.

Based on my knowledge, the financial statements, and other financial information included in this annual report, fairly present in all material respects the financial condition, results of operations and cash flows of the Registrant as of, and for, the periods presented in this annual report;



4.

The Registrant's other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-14 and 15d-14) for the Registrant and we have:



a)

designed such disclosure controls and procedures to ensure that material information relating to the Registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this annual report is being prepared;



b)

evaluated the effectiveness of the Registrant's disclosure controls and procedures as of a date within 90 days prior to the filing date of this annual report (the "Evaluation Date"); and



c)

presented in this annual report our conclusions about the effectiveness of the disclosure controls and procedures based on our evaluation as of the Evaluation Date;




5.

The Registrant's other certifying officer and I have disclosed, based on our most recent evaluation, to the Registrant's auditors and the audit committee of Registrant's board of directors (or persons performing the equivalent function):



a)

all significant deficiencies in the design or operation of internal controls which could adversely affect the Registrant's ability to record, process, summarize and report financial data and have identified for the Registrant's auditors any material weaknesses in internal controls; and



b)

any fraud, whether or not material, that involves management or other employees who have a significant role in the Registrant's internal controls; and




6.

The Registrant's other certifying officer and I have indicated in this annual report whether or not there were significant changes in internal controls or in other factors that could significantly affect internal controls subsequent to the date of our most recent evaluation, including any corrective actions with regard to significant deficiencies and material weaknesses.

Date: March 28, 2003 /s/  MICHAEL S. WYZGA Michael S. Wyzga
Chief Financial Officer

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DOCUMENTS INCORPORATED BY REFERENCE
EXPLANATORY NOTE
SIGNATURE
CERTIFICATION
CERTIFICATION