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Exhibit 23

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

        We hereby consent to the incorporation by reference in the Registration Statements on Form S-3 (File Nos. 33-61853, 333-51790, 333-31548, 333-63802, 333-100727, 333-109179, 333-114290) and in the Registration Statements on Form S-8 (File Nos. 33-58359, 33-60437, 333-10003, 333-33249, 333-83677, 333-51906, 33-30007, 33-68208, 333-33265, 333-10005, 333-33251, 333-83669, 333-33291, 33-21241, 333-55126, 333-42371, 333-81275, 333-87967, 333-81277, 333-83673, 333-64103, 333-83681, 333-51872, 333-52202, 333-66130, 333-70310, 333-76762, 333-76766, 333-76768, 333-76770, 333-100722, 333-90514, 333-90512, 333-90510, 333-64095, 333-106691, 333-106692, 333-111314, 333-116650, 333-116651, 333-116653, 333-114184, 333-125723, 333-125724, 333-125726) of Genzyme Corporation of our report dated March 9, 2006, except for Note R, as to which the date is December 19, 2006 relating to the consolidated financial statements, management's assessment of the effectiveness of internal control over financial reporting and the effectiveness of internal control over financial reporting, which appears in the Current Report on Form 8-K of Genzyme Corporation dated December 19, 2006.

/s/ PricewaterhouseCoopers LLP
Boston, Massachusetts
December 19, 2006

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Exhibit 23