Prior to the designation of a trauma system in Orange County, Calif, 73% of the in-hospital non-CNS deaths secondary to motor vehicular trauma were judged by the autopsy method to have been preventable. In June 1980, a regional system of trauma care with designated trauma centers was established in Orange County. We used the autopsy method to evaluate the first year's experience with this new system and compared the results with previous studies in Orange County for 1974, San Francisco County in 1974, and Orange County in 1978-1979. The results indicate a severe reduction in the number of deaths judged preventable. In addition, a more aggressive approach to the traumatized patient was noted as indicated by an increased percentage of patients who received appropriate surgical intervention.