Despite the advent of sophisticated diagnostic technology the diagnosis of the surgical abdomen in the Intensive Care Unit continues to pose a problem for the surgeon. A retrospective analysis was carried out to evaluate the utility of diagnostic peritoneal lavage to diagnose intra-abdominal surgical disease. Diagnostic peritoneal lavage was carried out in patients in whom the physical exam was deemed unreliable, such as in patients with cardiopulmonary instability or mental obtundation. Patients were included in the study if autopsy or laparotomy confirmation of the lavage data was available. Forty four patients met the inclusion criteria and formed the basis of this study. Of the twenty three patients with a positive lavage, three false-positive diagnostic peritoneal lavages were discovered, either at laparotomy or postmortem exam. Of the twenty one patients where diagnostic peritoneal lavage was negative, no false-negatives were discovered at autopsy or laparatomy. Therefore, this test is 100 per cent sensitive and 88 per cent specific. It is concluded that a negative diagnostic peritoneal lavage makes intra-abdominal surgical disease highly unlikely. However, a positive lavage may require further diagnostic work-up.