PURPOSE: To evaluate and compare the clinical and radiological outcome of bipolar hemiarthroplasty and second generation intramedullary nailing for elderly unstable peritrochanteric femoral fracutre. MATERIALS AND METHODS: From January 2000 to July 2004, 56 elderly unstable peritrochanteric fractures were treated with a bipolar hemiarthroplasty (34 cases) or a ITST intramedullary nailing (22 cases). The fractures were classified using the OTA/AO classification. The clinical results were evaluated by walking capability, hip joint pain, and thigh pain. The radiological results were evaluated on the basis of the radiographs at follow-up. RESULTS: In bipolar hemiarthroplasty group, The mean operation time was 134 minute, the mean blood loss was 648 ml. In intramedullary nailing group, The mean operation time was 103 minute, the mean blood loss was 386 ml. There were no different walking ability between prefracture and postoperative state in 22 cases (65%) of bipolar hemiarthroplasty group, 18 cases (80%) of intramedullary nailing group respectively. There were 5 cases (14%) hip joint pain in bipolar hemiarthroplasty group and 4 cases (18%) thigh pain in ITST intramedullary nailing group postoperatively. CONCLUSION: Comparing the operation time, blood loss, and walking ability, ITST intramedullary nailing group show superior clinical outcomes than bipolar hemiarthroplasty group. However, The effort for decreasing postoperative thigh pain might be required.