Femoral neck fractures following internal fixation for ntertrochanteric fractures are rare. From 1979 to 1998, 5 patients with this complication were found in our hospital. The possible reasons for these fractures were due to stress riser fractures caused by using too short lag screw, or due to severe osteoporosis resulting in insufficiency fractures. The stress riser fractures could be preventer by using a lag screw with adequate length (screw tip reaches 0.5 to 1.0 cm from the subchondral cortex), but the insufficiency fractures are hard to be prevent-ed.