In a follow-up study of 239 consecutive patients with fractures of the femoral neck treated by six surgeons in one hospital by Pugh nailing, Austin Moore prosthesis, or Knowles pinning, 96 per cent could be followed for a minimum of two years or until a definitve result had been reached. The incidence of unsatisfactory results was 39.3 per cent after Pugh nailing, 18.2 per cent after prosthetic replacement, and 14.2 per cent after Knowles pinning (mostly undisplaced or impacted fractures). Thirty-five unsatisfactory results following Pugh nailing were due to: aseptic necrosis which was definite in eighteen cases and probable in two; early mechanical failure in twelve cases; infection in one; and late non-union in two. Eight poor results followed prosthetic replacement and were due to erosion of the acetabulum in six and dislocation in two. The four poor results that followed Knowles pinning were due to aseptic necrosis in three and to pain, probably the results of aseptic necrosis, in another. From this study it was concluded that aseptic necrosis was more influenced by the original displacement than by the accuracy of reduction or fixation, and that in displaced femoral-neck fractures in the elderly, prosthetic replacement gave a more reliable result.