Bateman's single-assembly total hip prostheses were used in 18 cases of fracture of the femoral neck and aseptic necrosis of the femoral head from August 1980 to march 1981. 12 patients were discharged with satisfactory ambulatory status, while 6 patients showed poor results. Prolonged period between the onset of injury and the time of the operation appeared to be the main cause of the poor results. Cases of good results showed no pain and appeared to have better range of motion comparing with other femoral prostheses.