One hundred twelve comminuted or rotationally unstable fractures of the femur were treated with the Grosse-Kempf interlocking nail. Two-thirds of the fractures had comminution involving more than 50% of the cortex. Of the 112 nailings, 82 were static and 30 dynamic. Clinical and radiographic fracture union occurred in 98% of cases; there were two nonunions. There were no instances of deep wound infection or osteomyelitis. Only two patients had a change of limb length greater than 1 cm. Angulation in any plane greater than 10 degrees was noted in three patients (2.5%). External rotation deformities occurred in eight patients (7.0%). The interlocking nail has expanded the indications for the use of closed intramedullary nailing in the treatment of complex fractures of the femur. The incidence of infection and nonunion is remarkably low. Immediate stability of the fracture allows for immediate mobilization of the patient, early rehabilitation of the limb, and a shorter hospital stay.