Exhibit 23 CONSENT OF INDEPENDENT ACCOUNTANTS We hereby consent to the incorporation by reference in the Registration Statements on Form S-3 (File Nos. 33-82982, 33-97024, 333-25769, 333-49497, 333-59245, 333-50874) and Form S-8 (File Nos. 33-69516, 33-69518, 33-69520, 33-84706, 333-50874, 33-88030, 33-02970, 33-92998, 333-04535, 333-29059, 333-29977, 333-34119, 333-38490, 333-38494, 333-56747, 333-56749, 333-80623, 333-91468, 333-91470) of GTC Biotherapeutics, Inc. of our reports dated March 4, 2003 relating to the financial statements and financial statement schedule which appear in this Form 10-K. We also consent to the reference to us under the heading "Selected Financial Data" in this Form 10-K. PricewaterhouseCoopers LLP Boston, Massachusetts March 28, 2003