For the purpose of developing the ceramic artificial hip joint, we carried out biological and mechanical experiments. Tiny blocks of polycrystalline ceramic were inserted into the femurs of rabbits. Also, ceramic powder was injected into the knee joints of rabbits. Biological reaction were examined after varying intervals. It was proved, as a result, that ceramics have good affinity with living tissue. As a next step, wedge-shaped test pieces were inserted into the distal end of the femurs of dogs and tensile tests were carried out to investigate the degree of fixation of ceramic with bone. The result was that ceramic test pieces showed firmer fixation than those of metal. In the hip joints of five dogs, ceramic total hip prostheses for dogs were implanted. The dogs were autopsied after varying intervals and investigated histopathologically and scanning electron microscopically. Fixation of the socket and the prosthesis with the bone was superior to those made of metal and, moreover, virtually no wearing had taken place. However, the socket or prosthetic stems in four dogs were observed damaged in some parts. From the above mentioned, it is evident that when making ceramic total hip prostheses, we have to select ceramics of good quality and thicken their weightconcentrated parts by a device of its own design or use partly metal components coated with ceramic.