PURPOSE: This study examined the clinical course of subtrochanteric fractures of the femur as well as the risk factors of complications. MATERIALS AND METHODS: A retrospective study was performed on 56 patients with femoral subtrochanteric fractures who were treated at our hospital from 2004 to 2008. Risk factors, such as the type of fracture, type of implant, soft tissue dissection at the fracture site, communition of the medial cortex and degree of fracture displacement after the reduction, were compared to determine their effect on the rate of complications, such as nonunion and implant failure. Open reduction with a soft tissue dissection at the fracture site was performed in 34 cases, and a closed reduction was performed in 22 cases. Thirty five cases had medial cortex communition and 21 cases did not. RESULTS: There were 8 cases of nonunion(14.3%). There was a positive correlation between the degree of fracture displacement after the reduction and the union time (P=0.017). The union time was longer when there was communition of the medial cortex. A subtrochanteric fracture using an open reduction tended to have a long union time but this was not statistically significant. There was no correlation between the type of implant and union time. CONCLUSION: The union time is longer in subtrochanteric fractures with communition of the medial cortex. Therefore, it is important to preserve the blood supply at the fracture site using a closed reduction and restore the fracture reduction accurately.