Five skeletally immature patients developed premature closure of the greater trochanteric physis consequent to placement of an intramedullary rod for primary treatment of a femoral diaphyseal fracture. Each patient developed increased femoral neck valgus as compared with the contralateral hip. To date, however, none of these patients has had any functional disability, although one has developed mild radiographic subluxation. In addition, anatomic specimens demonstrated the likelihood of traversing a portion of the greater trochanteric physis. Other methods of fracture treatment, either operative or nonoperative, should be considered in skeletally immature patients who have not entered the final phase of skeletal maturation characterized by subchondral "sclerosis" along the greater trochanteric physis.