An impact to the head has been the most frequent cause of life threatening injury to racing drivers, and protecting the driver's head is of prime importance. A head protection system must ensure that any loads or accelerations imparted do not exceed those which may cause injury. The aim of this work was investigate a number accidents during which a head injury or a substantial head impact occurred, in order to provide a better understanding of accident kinematics and head injury mechanisms. This work has been extremely important in providing detailed data on driver tolerance to head injury, for both translational and rotational motion, which both contribute significantly to injuries sustained during head impact. This work has indicated that the threshold for driver head injury may be somewhat higher than current published and accepted criteria. The results from this study will provide valuable information to ongoing FIA-TRL research into motorsport safety.