A study of brain injury biomechanics has been conducted using detailed reconstruction of real world injury events. A total of nineteen head injury cases were identified in neurosurgery wards of two hospitals in Sweden. From these cases, nine were subjected to detailed reconstruction techniques to quantify the head loading causing the injuries. Output of the analyses included the kinematics of the head and contact loads. Reconstructions of vehicle and occupant dynamics were conducted primarily with computer simulation tools with some limited mechanical testing using vehicle components and Hybrid III dummies. Results of the study indicate that computer simulation resources are maturing to the point where useful biomechanical information can be obtained through the reconstruction of injury events. The flexibility of the computer models, compared to mechanical dummy testing, is an attractive research approach. Objective evaluation procedures were identified that allowed the quality of the reconstruction to be assessed. Preliminary output of the brain injury research indicated considerable rotational motions of the head were involved in all the brain injuries investigated. Angular accelerations above 5000 rad/s2 were always associated with brain injuries and no head injury was attributed to pure linear accelerations of the head.