A prospective study was carried out to assess the incidence and type of complications after non-therapeutic operations for penetrating trauma. A total of 372 operations were performed on 368 patients with penetrating injuries to the abdomen (240 procedures), chest (49), neck (48) and extremities (35). There were 46 negative or non-therapeutic operations. The incidence of major complications directly related to anaesthesia or operation in this group of patients was 4 percent (two patients). The operation might have contributed to a further three major complications. The mean hospital stay for patients undergoing uncomplicated non-therapeutic operation was 4.1 days; for those with complications it was 21.2 days. It is concluded that non-therapeutic operations for penetrating trauma carry a significant morbidity rate. A policy of selective conservatism is advocated.