Injury patterns of fatally injured motor vehicle occupants in side impact crashes were examined based on crashes in the United Kingdom during 1981-85. Detailed Coroners’ records for 91 struck side and 49 opposite side fatalities were assessed. The characteristics of the side impact crashes and the fatally injured occupants were described, and possible countermeasures that could have prevented the fatality based on existing technology were identified. Occupants killed in side impact crashes had a high incidence of head and chest injuries; severe injuries to multiple body regions were common. Opposite side fatalities were more likely to sustain serious head injuries than were struck side fatalities. Forty-four percent of the fatalities were judged preventable using existing technology. In the present study stronger side structure and energy absorbing padding was the most common potential vehicle design countermeasure identified; this countermeasure alone was estimated to be capable of preventing 6 percent of the fatalities and an additional 11 percent when combined with other countermeasures. Additional design features addressing head injury in side impact crashes are needed to achieve further reductions in fatalities.