UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 15

CERTIFICATION AND NOTICE OF TERMINATION OF REGISTRATION UNDER SECTION 12(g) OF THE SECURITIES EXCHANGE ACT OF 1934 OR SUSPENSION OF DUTY TO FILE REPORTS UNDER SECTIONS 13 AND 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934.

Commission File Number:  0-14680

GENZYME CORPORATION

(Exact name of registrant as specified in its charter)

1500 Kendall Street

Cambridge, Massachusetts

(617) 252-7500

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Common Stock, $0.01 par value

3.625% Senior Notes due 2015

5.000% Senior Notes due 2020

(Title of each class of securities covered by this Form)

None

(Titles of all other classes of securities for which a duty to file reports under section 13(a) or 15(d) remains)

Please place an X in the box(es) to designate the appropriate rule provision(s) relied upon to terminate or suspend the duty to file reports:

Rule 12g-4(a)(1)	x
Rule 12g-4(a)(2)	¨
Rule 12h-3(b)(1)(i)	x
Rule 12h-3(b)(1)(ii)	¨
Rule 12h-3(b)(2)	¨
Rule 15d-6	¨

Approximate number of holders of record as of the certification or notice date:         

Common Stock, $0.01 par value: 1

3.625% Senior Notes due 2015: 34

5.000% Senior Notes due 2020: 27

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, Genzyme Corporation has caused this certification/notice to be signed on its behalf by the undersigned duly authorized person.

Date: April 18, 2011

GENZYME CORPORATION
By:	/s/ Michael S. Wyzga
	Name: Michael S. Wyzga
	Title: Executive Vice President, Finance and           Chief Financial Officer