For the development of new implantable biomaterials as bone substitutes in the treatment of jaw bone defects, bone morphogenetic protein (BMP) bound to porous beta-tricalcium phosphate (beta-TCP) was investigated in the present experimental study in mice. The BMP was extracted from bovine cortical bone while the beta-TCP was synthesized by a mechanochemical method. The affinity of BMP to beta-TCP was examined by means of beta-TCP column chromatography. The porous beta-TCP combined with the BMP by dialysis was implanted in the muscle pouches of mice. The beta-TCP or BMP alone was also implanted in the same places in the controls. Three weeks after the implantation a new bone formation was observed in the exterior surface of the beta-TCP/BMP complex, but not in that of the beta-TCP control. The quantity of bone induced by the beta-TCP/BMP complex was determined on the X-ray film by a computer supported image analysis system. The osteoinductive activity of the complex was higher than that of the BMP alone. The histological relationship between the beta-TCP/BMP complex and the original tissues was excellent. The result of the present study may indicate that the beta-TCP/BMP complex can be used as an osteogenetic biomaterial for the treatment of bone tissue defects.