FRAMINGHAM, MA – December 23, 2008 – GTC Biotherapeutics, Inc. ("GTC", Nasdaq: GTCB) has closed on the agreement with LFB Biotechnologies for a $15 million financing in which GTC issued convertible debt and warrants to purchase shares of GTCB common stock on the terms previously disclosed. The net proceeds at closing, after transaction costs and establishment of a restricted cash account, were approximately $10 million.

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 Europe and has begun the review process in the United States under a Biologics License Application. 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 used for the treatment of hemophilia, and alpha-1 antitrypsin. GTC also has a monoclonal antibody portfolio that includes a monoclonal antibody to CD20 and a monoclonal antibody to CD137. GTC is collaborating with LFB on the factor VIIa, factor IX, alpha-1 antitrypsin, and CD20 monoclonal antibody programs. 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.