The total knee replacement is an excellent method for the treatment of osteoarthritis, rheumatoid arthritis, etc. of the knee joint. The tendency of the use of total knee prosthesis is increasing now in Korea. But domestic production of the prosthesis is not avaliable and all are imported from abroad. Moreover, these prosthesis are not well adapted to Korean people, and in occation, the custom-made prosthesis should be needed. So, domestic production of the prosthesis is required. For production of new prosthesis, in cooperation with KAIST(Korea Advanced Institute of Science and Technology), we developed the new alloy 15-57 for total knee prosthesis. We conducted an animal experimental study to confirm the biocompatibility of the new alloy. In this experiment, the Zimmer^® company vitallium was compared with this new alloy as control study. The results are as follows: 1. Biocompatibility of the new alloy 15-57 is similar than that of Zimmer^® company vitallium in histological study of metal-bone interspace area. 2. Surface corrosion of both metal was nearly absent. 3. In summary, the new alloy 15-57 is suggested as an acceptable metal for the production of total knee prosthesis.