Atypical femur fractures represent a new disease entity associated with the use of oral bisphosphonates. This review summarizes the current understanding of this phenomenon. These fractures are usually transverse, affecting the proximal third of the femoral shaft. They occur after minor or no trauma, include a thickening of the lateral femoral cortex, a delayed consolidation time and prodromal symptoms. In this context, the risk/benefit ratio of bisphosphonates remains favorable if the indication is adequate. In case of fracture, indication to treatment should be reevaluated. Pain or discomfort in the thigh in a patient receiving bisphosphonate should lead to radiological investigations in order to detect the possible occurrence of a stress fracture.