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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 14, 2005, except for Note R, as to which the date is June 24, 2005 relating to the consolidated financial statements, financial statement schedule, 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 June 28, 2005.

/s/ PricewaterhouseCoopers LLP
Boston, Massachusetts
June 27, 2005

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Exhibit 23