We evaluated 245 cases of comminuted femoral fractures treated by intramedullary nailing and graded them by fracture pattern and degree of stability as segmental fractures, and grade I, grade II, grade III, and grade IV comminuted fractures. The infection rate was 0.4 per cent, and the nonunion rate was 0.8 per cent. Shortening of more than 2 cm. was seen in seven cases (3 per cent), and malrotation of more than 20 degrees was noted in four cases (1.7 per cent). These more common problems of shortening and rotation were almost eliminated by the increased use of cerclage wire and postoperative traction and spica casts. Knee range of motion averaged 128 degrees. These fractures provide interesting and difficult challenges. Intramedullary nailing of the segmental fractures is technically demanding but offers excellent results in these otherwise difficult fractures. Patients with grade I and grade II comminuted fractures do well with intramedullary nailing and the bones remain stable. Grade III and grade IV comminuted fractures are unstable and pose the risk of shortening and rotation. Therefore, to gain anatomic restoration in a young person we believe that it is reasonable to perform an open reduction and cerclage wiring of these fractures. The postoperative treatment of the comminuted femoral fracture is determined by both fracture stability and patient reliability, and frequent roentgenograms are indicated. Most importantly, the surgeon should be prepared to apply whatever form of treatment he believes to be necessary to gain optimal results in each individual.