Early diagnosis is the key to successful treatment of slipping of the upper femoral epiphysis. The diagnosis can be made with certainty from the history, the physical signs, and the characteristic roentgenographic picture. Treatment should be instituted at once and should be carried through until bony fusion has occurred between the head and the neck. This can be secured by either a Smith-Petersen nail, or a bone graft, or bone screws, or impaction, or the drilling method.