The difference in osteogenesis of the periosteal graft and the effects of changing the recipient environment were studied in 26 young and 16 adult rabbits. The periosteal grafts from bilateral tibiae were implanted to the right and left sides of the abdominal wall, on the right side a coagulum was added. For quantitative examination, radionuclide, CT, ion-selective electrode, atomic absorption spectrometry and biochemical autoassay methods were used. The results showed that osteogenesis of periosteal grafts may increase by changing the local environments. The amount of periosteal bone formed in the adult rabbits was obviously less than in the young. The bone formation of the periosteal grafts with a coagulum, especially in the adults was increased. The possible mechanism of increasing periosteal osteogenesis by the coagulum is discussed.