A sideways fall onto the hip is known to be a clear risk factor for hip fracture of elderly people, but it has remained unclear how severe injury such a fall can be. This retrospective patient file survey of young adults aged 15 to 49 years suggested that a fall onto the hip is indeed a serious high-impact injury possessing energy to fracture the proximal femur even in young healthy men. This being the case, it is evident that sideways falls can be very dangerous and thus a natural target for fracture prevention.