A comparison was made regarding the observed frequency of intraperitoneal complications between two groups of patients operated upon for perforated appendicitis during a 5-year period (1968-73). The two groups, corresponding to two different general surgical departments at the same hospital, were given different forms of adjuvant treatment. The first group (78 patients) received postoperative intraperitoneal lavage, with antibiotics added to the lavage solution. In the other department (77 patients), the peritoneal cavity was drained postoperatively. No lavage was performed in this group, but antibiotics were given systemically. Sixteen patients in the drainage group developed intraperitoneal complications, as compared with 5 in the lavage group.