Objective. To show 3 cases of subtrochanteric fracture as complication of screw fixation for femoral neck undisplaced fractures. Material and methods. We present 3 cases of subtrochanteric fractures after screw fixation of valgus impacted femoral neck fractures. In all cases, intramedulary nailing was the treatment choice for this complication. Results. One year after the surgery all fractures healed without needing additional procedures and all patients walked pain-free. Discussion. The results of percutaneous fixation of undisplaced fractures of the femoral neck using cannulated screws are good in aged patients. Subtrochanteric fracture is a rare complication. Most authors attribute it to wrong surgical technique. These errors represent weakening and more direct transmission of forces on the lateral cortex. We provide several advices to avoid the failure. Conclusions. The best way to avoid this complication is an appropriate surgical technique. The treatment of choice, if present, is the intramedullary nailing