Repair of bone defect by compound of bone morphogenic protein (BMP) and its prior bone matrix gelatin (BMG) was compared with repair by BMP with hydroxyapatite(HA). The results showed that the BMP/BMG group was found fibrous callus in the bone defect in 4th week. In 8th week a large quantity of osseos trabecula was found. In 12th week the BMP was absorbed completely and was replaced by newly formed bone. In 16th week the recanalization appeared in the bone cavity. While in the BMP/HA group, although the fibrous callus was appeared in the 4th and 8th weeks, the HA was not absorbed. In the 12th and 16th weeks the change was similar to that in the 8th week and no recanalization of bone marrow cavity. It was suggested the BMP/BMG compound might be an ideal material to repair the bone defect.