PURPOSE: To evaluate the availability of bone scan as a preoperative study by analyzing patients who developed ipsilateral femoral neck fractures during intramedullary nailing for femoral shaft fractures. MATERIALS AND METHODS: Among 28 patients who conducted preoperative bone scan before performing intramedullary nailing for femoral shaft fractures, three patients developed femoral neck fractures during the operation. We analyzed retrospectively the result of bone scan including clinical and radiological findings of three patients. RESULTS: Among 28 patients, 7 showed hot uptake in femoral neck area compared to the unaffected side in preoperative bone scan; All 3 patients who developed femoral neck fractures during the operaion showed hot uptakein the area. Among 7 patients who showed hot uptake, there were no abnormalities in plain radiograph and computerized tomography of femoral neck area. CONCLUSION: The risk of femoral neck fracture should be considered during the intramedullary nailing for femoral shaft fracture, if there was hot uptake in femoral neck area in preoperative bone scan.