To determine the roles of diagnostic peritoneal lavage (DPL) and abdominal computed tomography (CT) in the evaluation of blunt abdominal trauma, we compared our results in the eras before and after the advent of abdominal CT. In the pre-CT era 1977 to 1980 (group 1; 365 patients), DPL was the diagnostic procedure of choice. In the CT era 1983 to 1986 (group 2; 282 patients), DPL was used for unstable, polytraumatized patients, and CT was reserved for stable patients. The rate of delayed recognition of documented visceral injury (7%) was similar for groups 1 and 2. Celiotomy was nontherapeutic in 21 (14%) patients in group 1 and in 5 (5%) in group 2 (p less than 0.02). Despite immediate availability of abdominal CT, clinical examination alone or in combination with DPL was the diagnostic procedure of choice in 41% of those with blunt abdominal trauma in group 2. The complementary use of abdominal CT and DPL in those with blunt abdominal trauma decreased the rate of nontherapeutic celiotomy, did not result in a significant increase in missed injuries, and allowed identification of candidates for nonoperative management of solid organ injury.