GTC BIOTHERAPEUTICS TO HOST FOURTH QUARTER AND YEAR END 2009 EARNINGS CALL AND WEBCAST ON FRIDAY, MARCH 12, 2010

Framingham, Mass., March 5, 2010 -- GTC Biotherapeutics, Inc. (Nasdaq: GTCB) (“GTC”) announced today that its financial results for the fourth quarter and year end 2009 will be released on Friday, March 12, 2010 followed by a webcast conference call starting at 10:00 a.m. Eastern Time. You may access the live internet broadcast or the subsequent archived recording, on GTC’s website at http://www.gtc-bio.com or access the conference call as follows:

Live Call – In the United States, dial 1-877-407-0778
Outside the United States, dial 201-689-8565

Audio Archive – In the United States, dial 1-877-660-6853
Outside the United States, dial 201-612-7415
Reference call ID: when prompted Account #: 286 Conference ID #: 346748

About GTC Biotherapeutics

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 therapeutic product produced in transgenic animals to be approved anywhere in the world. Building upon the 2009 FDA approval of ATryn®, GTC is collaborating with its US commercialization partner, Lundbeck Inc., to develop a protocol for a pivotal study of patients with acquired antithrombin deficiencies in cardiac surgery. GTC aims to initiate a clinical trial in this indication in the second half of 2010.

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 patients with hemophilia, and recombinant alpha-fetoprotein, which is being developed for the treatment of Myasthenia Gravis and Multiple Sclerosis. GTC plans to advance its human recombinant factor VIIa program into a Phase I clinical study in the first half of 2010 and its alpha-fetoprotein program into a Phase II study in Myasthenia Gravis in the second half of 2010 after securing a partner for that program.

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 enable 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.