The experience at University Hospitals of Cleveland and Children's Hospital of Akron with fifty cases of acute slipped capital femoral epiphysis is reviewed. In forty-seven hips treated by manipulative reduction and epiphyseodesis, pin fixation, or both, seven cases of avascular necrosis occurred (15 per cent). In nineteen hips treated by manipulative reduction, epiphyseodesis, and plaster immobilization, one case of avascular necrosis occurred (5 per cent), and seventeen (90 per cent) satisfactory functional results were obtained. In sixteen hips treated by manipulative reduction and pin fixation, three cases of avascular necrosis occurred (25 per cent), and twelve (75 per cent) satisfactory functional results were obtained. No case of avascular necrosis occurred in eight patients treated by manipulative reduction within twenty-four hours of the onset of acute symptoms. No case of avascular necrosis occurred in a female patient.