It has been widely reported that injury to the leg is the most common form of non-fatal trauma associated with motorcycle accidents. Furthermore, it has also been reported that the majority of motorcycle leg injuries resemble those experienced by pedestrians in that they do not involve crush. Rather, these injuries appear to involve only a direct impact between the leg and an opposing rigid object. Often the soft tissue of the limb is injured from the inside out in that sharp bone fragments and jagged ends lacerate the soft tissue as relative motion occurs. The complexity of understanding these results is due to a combination of impact effects, biological material properties and human geometric considerations. Our ongoing research, underway for several years, is providing the fundamental data for cadaver leg and bone impact response. This research is sponsored by the Japan Automobile Manufacturers Association (JAMA), Inc. for the investigation of design modifications to automobiles and motorcycles for reducing the seriousness of collision injuries. To conduct this research a unique test facility has been developed that simulates collisions between automobiles and pedestrians, motorcycles, or bicycles. Results are presented and discussed for the purposes of understanding fracture behavior of the human leg and tibia.