<DOCUMENT>
<TYPE>EX-21
<SEQUENCE>10
<FILENAME>a2042599zex-21.txt
<DESCRIPTION>EXHIBIT 21
<TEXT>

<PAGE>

                                                                    Exhibit 21

                        SUBSIDIARIES OF THE REGISTRANT

<TABLE>
<CAPTION>

                                                                                             JURISDICTION OF
NAME                               DIRECT PARENT                   OWNERSHIP                  INCORPORATION
----                               -------------                   ---------                 ---------------
<S>                                <C>                             <C>                       <C>

Allston Landing                    Genzyme Corporation              100%                     Massachusetts
Corporation

Allston Landing                    Genzyme Corporation              100%                     Massachusetts
Corporation II

BioMarin/Genzyme LLC               Genzyme Corporation               50%                     Delaware

Diacrin/Genzyme LLC                Genzyme Corporation               50%                     Massachusetts

GelTex Pharmaceuticals, Inc.       Genzyme Corporation              100%                     Massachusetts

Genzyme Biosurgery
Corporation                        Genzyme Corporation              100%                     Massachusetts

Genzyme B.V.                       Genzyme Corporation              100%                     Netherlands

Genzyme GmbH                       Genzyme B.V.                     100%                     Germany

Genzyme France S.A.                Genzyme B.V.                     100%                     France

Genzyme Limited                    Genzyme Corporation              100%                     United Kingdom

Genzyme Securities                 Genzyme Corporation              100%                     Massachusetts
Corporation

Genzyme Transgenics                Genzyme Corporation               26%                     Massachusetts
Corporation

Genzyme Virotech GmbH              Genzyme Corporation              100%                     Germany

Genzyme/Pharming Alliance LLC      Genzyme Corporation               50%                     Delaware

Pharming/Genzyme LLC               Genzyme Corporation               50%                     Delaware

RenaGel LLC                        Genzyme Corporation              100%                     Delaware

</TABLE>
</TEXT>
</DOCUMENT>