The relationship between blunt abdominal trauma and intra-abdominal abscess (IAA) is discussed infrequently; therefore we conducted a retrospective review of 4050 multiple blunt trauma admissions from January 1986 to July 1988. Of 325 patients who had a laparotomy for blunt abdominal trauma, we identified 15 (4.6%) who had 40 IAAs. The most common intra-abdominal injuries involved the spleen and liver. Splenectomy increased the risk for IAA in contrast to splenic salvage. Blunt injuries to the kidney and pancreas, when occurring in multiple trauma patients, carried a significant risk of IAA. Associated multiple extra-abdominal injuries and high transfusion requirements increased the risk for IAA formation. Most of the IAAs were located in the upper quadrants. There was a 46% incidence of multiple IAA, which in turn had an 80% chance of recurrence after initial drainage. Enterobacter species played an important role in the formation of IAA in our trauma patients. Three patients (20%) died. Poor prognostic indicators included a high injury severity score, high transfusion requirements, the presence of pelvic fracture, positive blood cultures, multiple organisms per abscess, and multiple-organ system failure.