1. Nine cases of fracture of the femur after prosthetic arthroplasty are presented. 2. These fractures occurred in the trochanteric area, and in the proximal, middle, and distal portions of the femoral shaft. 3. Methods of treatment for fractures in each of these four locations are discussed. 4. A method of intramedullary nailing for fractures of the upper and middle portions of the shaft is presented in which the prosthesis is not disturbed.