The regionalization of trauma care has led to a decrease in preventable death after injury. This decrease has been attributed to earlier resuscitation and surgical intervention. Little emphasis, however, has focused on the critical care phase of trauma patient management. This study was undertaken to determine the significance of critical care errors (CCEs) on preventable mortality and morbidity in a regionalized system of trauma care. The records of 12,910 trauma patients admitted to six trauma centers over a three-year period were reviewed. The cause and preventability of death was determined by a panel of trauma experts. Critical care errors occurred in 151 (23%) of all patients with errors occurring during any phase of care. The CCEs were identified in 38 of 125 (30%) deaths of patients with errors in some phase of care. The CCEs were implicated as the cause of death in 30 (48%) of the 62 preventable deaths. The proportion of preventable deaths attributable to CCEs was higher than the proportion of preventable death attributable to errors in the resuscitative and operative phases of care (p less than 0.001, chi-square). These data indicate that CCEs significantly contribute to preventable mortality and morbidity in trauma patients. It is imperative that physicians caring for trauma patients possess expertise in the critical care management of injured patients.