A new application of operative ultrasound to help assess the fracture alignment for closed reduction and passing the guide wire in closed femoral nailing is described. This method can be used instead of fluoroscopic monitoring in certain important steps which can markedly reduce the exposure time of fluoroscopic monitoring. Nine of ten cases were successful using this technique for closed unlocked nailing with an average ultrasound monitoring time of 8 minutes. The time required for fluoroscopic assessment was reduced to less than 1 minute for each successful case.