Subtrochanteric fracture of the femur are difficult to treat successfully. Although performing operative treatment, the incidence of mechanical complication is higher than other sites of long bones. During the period of January. 1990 to June. 1995, twe nty-four cases of subtrochanteric fracture of femur were treated by Interlocking intramedullary nail at the Department of Orthopedic Surgery, Gil Hospital, Incheon, and the results were obtained as follows : 1. Associated injuries, which were common in lower limb(7 cases), pelvic bone(3 cases) and upper limb(4 cases) made a fracture more difficult to treat. 2. Fieldings type III(12 cases) fracture and Seinsheimers type II(18 cases) fracture and Russel-T aylors Type I A(19 cases) fracture and Winqist-Hansen Type II(13 cases) fracture were most common. 3. The average union time was 19.3 weeks. 4. The complications were three cases. : delayed union(1 case), infection(1 cases), angular deformity(1 case). 5. Interlocking nail is one of the good implant for rigid fixation of subtrochanteric fracture, especially mechanical characteristics of interlocking nail have eliminated the requirement of surgically reconstituting the medial femoral cortex.