In the present study, which was undertaken to elucidate the process of repair of the ischemic femoral head, the blood supply to the femoral heads of mature rabbits was interrupted artificially, and the forming process of new vessels was examined morphologically by microangiography and the findings were compared with histopathological findings. The results indicated that vessels penetrated the ischemic head in early stages after interruption of the blood supply, forming irregular network, becoming gradually increased in caliber and finally extending to the whole femoral head. Histologically, these vessels were capillaries in the beginning and became normal arterioles, finally. The repairing process progressed gradually and the tissues were restored almost to normal in 1 year. From these observations it is concluded that simple ischemia may be repaired completely and clinical osteonecrosis of femoral heads is probably due to the occurrence of ischemia due to secondary factors such as mechanical stress.