Abstract To understand the femoral head activity in old fracture of femoral neck, 159 cases from 1982 to 1994 were observed through X-ray film, pathological sections, transparent electronic microscope, tetracycline label technique and ECT examination. The results showed that under a status without stress, the avascular femoral head tended to be repaired in its natural way. The collapse of femoral head was caused by stress to some extent duringthe active repair process. Great attention should be paid in treating fracture of femoral neck that load should never be put on the femoral head during the process of fracture healing.