PURPOSE: Antegrade intramedullary nailing of the femur is effective method of treatment for patients with femoral shaft fractures. But retrograde IM nailing is another effective method, especially in femoral shaft fractures concomitant with ipsilateral femoral neck, intertrochanteric fractures, acetabular fracture, multiple fracture and obesity, pregnancy, traumatic arthrotomy of the knee joint, bilateral femur fractures, and floating knee injuries are also indicated. The purpose of this study is to verify the effectiveness of retrograde IM nailing after long-term follow-up by retrospective evaluation. MATERIALS AND METHODS: A retrospective review of the medical charts and X-rays about 37 patients who were operated by retrograde nailing and all patients were minimally followed up about 2 years. Results were evaluated radiologically for screw breakage, nail migration, nonunion and clinically for knee ROM limitation, infection. RESULTS: The results were as follows; 1) union was achieved at on average of 17 weeks. 2) Full range of knee motion was gained in 33/37 cases. Knee-stiffness occurred in 4 cases, Severity of initial trauma might affect such results but not, retrograde nailing 3) 2 complications were found nonunion and delayed union. 4) There were not postoperative infection and femoral shortening. There were distal screw breakage in 4 cases but, the others were not migrated. CONCLUSION: Retrograde IM nailing of femoral fracture is an effective method in selected cases such as ipsilateral femoral neck fractures, floating knees, post-TKRA femoral fracture and so on. If retrograde IM nailing is operated by skillful surgeon and appled to absolute indication, the result is no significant difference of antegrade IM nail such as bone union, nonunion and postoperative infection. Nevertheless, operation time is shorter and blood loss lesser. Significant knee problems related to this technique could not be identified for 2 years followed up.