Peritoneal lavage has become widely accepted in the management of blunt abdominal trauma, but its role has not been clearly established in the evaluation of penetrating abdominal injuries. The interpretation of lavage effluent analysis and the criterion for laparotomy are also unclear. A review of our recent experience and that of other indicates that peritoneal lavage has a significant role in detecting intra-abdominal injury from abdominal stab wounds and penetrating injuries of the lower part of the chest. Peritoneal lavage has a limited role in the evaluation of abdominal gunshot wounds, that is, when penetration of the peritoneum is equivocal. It is of negligible value in the evaluation of penetrating trauma to the back and flank. Quantitation of erythrocytes in the lavage effluent is the most reliable indication of intra-abdominal injury, and the level of significance varies according to the mechanism and location of the injury. The usefulness of other analysis of the effluent remains undetermined.