GTC BIOTHERAPEUTICS TO WEBCAST ANNUAL MEETING ON MAY 27, 2009

Framingham, MA – May 22, 2009 -- GTC Biotherapeutics, Inc. (“GTC”) (Nasdaq: GTCB) will webcast its 2009 Annual Meeting of Stockholders on Wednesday, May 27, 2009 starting at approximately 2:00 p.m. Eastern Time. The annual meeting is to be held at the Forefront Center for Meetings & Conferences in Waltham, Massachusetts. GTC expects to conduct the formal business portion of the meeting followed by a presentation to its stockholders.

To access the 2009 Annual Meeting live via the Internet, please log onto www.gtc-bio.com approximately 15 minutes before the start of the meeting to allow for any software downloads that may be necessary. Following the webcast of the meeting, an archive will be available at the same address.

The webcast is also being distributed through the Thomson StreetEvents Network. Individual investors can listen to the meeting at www.earnings.com, Thomson’s individual investor portal, powered by StreetEvents. Institutional investors can access the call via Thomson StreetEvents (www.streetevents.com), a password-protected event management site.

GTC Biotherapeutics develops, supplies and commercializes therapeutic proteins produced through transgenic animal technology. ATryn®, GTC’s recombinant human antithrombin, has been approved for use in the United States and Europe. ATryn is the first and only product produced in transgenic animals to be approved for therapeutic use anywhere in the world. In addition to ATryn, GTC is developing a portfolio of recombinant human plasma proteins with known therapeutic properties. These proteins include recombinant forms of human coagulation factors VIIa and IX, which are being developed for the treatment of hemophilia. GTC is also developing a portfolio of follow-on biologic monoclonal antibodies and a CD20 antibody with enhanced ADCC (antibody-dependent cell-mediated cytotoxicity). GTC’s intellectual property includes a patent in the United States through 2021 for the production of any therapeutic protein in the milk of any transgenic mammal. GTC’s transgenic production platform is particularly well suited to enabling cost effective development of proteins that are difficult to express in traditional recombinant production systems as well as proteins that are required in large volumes. Additional information is available on the GTC web site, http://www.gtc-bio.com.