PURPOSE: To evaluate the effectiveness. analyze the result after retrograde intramedullary (IM) nailing in femoral shaft fracture MATERIALS AND METHODS: Thirty-four femoral shaft fracture (32 patients) were operated with retrograde IM nail and followed the result for more than 18 month from march 2001 to march 2003. There were 6 of femoral mid shaft fractures and 28 of distal femur fractures. According to AO classification, there were 1 of A1, 1 of A2, 2 of A3, 2 of C1 in femoral mid shaft fracture and 11 of A1, 7 of A2, 7 of A3, 1 of B1, 2 of C1 in distal femur fracture. They included 5 open fracrures. By Gustilo classification there were 3 of type I, 2 of type II. Through radiologic study we evaluated the time of union, nonunion, malunion. And in clinical evaluation we checked knee function in 18 month after operation. RESULTS: It took 16 weeks (range 12~20 weeks) for average bone uion period. 30 cases out of 34 cases had the bone union but 4 cases showed nonunion. There were not any complication except 3 cases of screw migration. Full rage of motion was gained in 29 cases. However knee stiffness occurred in 5 cases. The knee function through knee score was assessed by showing 28 of excellent, 1 of good, 5 of poor. CONCLUSION: Even though the retrograde intramedullary nailing may have some defect to be able to damage to knee joint in operating, It can be useful surgical technique for femoral shaft fracture in such as ipsilateral fracture or multiple fracture, poor general condition, and so on.