Preventable deaths (PD) were evaluated by mechanism of injury for 13,500 trauma admissions to eight hospitals over 2 years. There were 42 (3.3%) hospital deaths. Preventable deaths were analyzed by time of death, anatomic site of injury, and mechanism; penetrating (PEN) and blunt with low fall (LF) injuries were considered separately. Preventability of death for patients with probability of survival of less than 0.5, "unexpected deaths," after penetrating and blunt injuries, was determined by consensus of three trauma surgeons. Twelve per cent of deaths were found to be possibly preventable. The incidence of preventable deaths did not differ significantly across groups. Factors in preventable deaths varied by injury cause; delays in operation, PEN (50%), and blunt injury patients (48%); management errors, blunt (52%) and LF (84%); and technical errors, PEN (37.5%). Median times to death were significantly different by cause of injury: PEN, 3 hours; blunt, 13 hours; and LF, 3975 hours. Problems were identified in the hospital care of patients, especially those with LF, leading to sepsis and multiple organ failure.