The radiation polymerization technique was used for immobilization testosterone propionate into crosslinked network of polyhydroxyethyl methacrylate to prepare slowly released male sex hormone drug which is used for testicular prosthesis. The testicular prosthesis was transplanted into the scrotum of male rabbit whose testes was excised 2 months before the transplantation. Then the level of male sex hormone in serum was measured by radioimmunoassay once a week after transplantation. The results of measurement in a period of 6 months were shown that the testicular prosthesis has a stable release of male sex hormone. The testosterone level in serum of the castrated male rabbits rises markedly and finally stablizes at the level of 429± 36ng/100 ml after transplantation. Mircoscopic examination of biopsies taken from the tissues around the testicular prosthesis showed that tissue compatibility was revealed well.