Interlocking intramedullary nailing for supracondylar and intercondylar fractures of the distal part of the femur. Thirty-seven fractures of the distal part of the femur in thirty-five patients were treated with interlocking intramedullary nailing. All fractures were nailed by a closed technique after any intercondylar extension of the fracture had been managed by reduction and stabilization with percutaneous lag-screws. Patients who had an isolated condylar fracture or a severely comminuted intercondylar fracture were treated with other types of implants. There were thirty extra-articular (type-A) fractures and seven intra-articular (type-C1 and type-C2) fractures. Postoperatively, early mobilization exercises and weight-bearing were begun. At an average duration of follow-up of 20.5 months (range, fifteen to twenty-six months), all thirty-seven fractures had healed. There were no malunions of either the supracondylar or the intercondylar fractures. Complications were infrequent and included chronic irritation from the distal screws in three patients and delayed union in one; the latter healed with two centimeters of shortening after bone-grafting. There were no infections. The functional results were assessed with the modified knee-rating system of The Hospital for Special Surgery. Thirteen knees (35 per cent) had an excellent result; twenty-two (59 per cent), a good result; and two (5 per cent), a fair result. The results correlated with the age of the patient and the presence of an intra-articular fracture. We concluded that closed interlocking intramedullary nailing is an excellent technique for both supracondylar and simple intercondylar fractures in which closed reduction and percutaneous fixation of the articular fracture is possible. 