Around 15% of all the traffic related fatalities in Europe are pedestrians. That is about 6500 fatalities in Europe. Head injury is the most severe injury in the pedestrian pattern and together with the lower extremities the only anatomical areas where countermeasures are currently applied. Head injury in the automotive industry is predicted through the Head Injury Criterion (HIC). All the countermeasures applied and all the regulations derived from them are focused on this criteria. The HIC only uses as an input the linear acceleration measured in the head Centre of Gravity. In this book rotational acceleration as a risk factor for traumatic brain injury in pedestrian–vehicle collisions has been evaluated, and compared with the main injury criteria accepted by the scientific community.