The value of extraperitoneal wound drainage and a 3-day course of prophylactic systemic cephaloridine used both separately and together have been assessed in a prospective controlled randomized trial involving 246 patients undergoing appendicectomy at the Leicester Royal Infirmary. Extraperitoneal wound drainage was shown to reduce significantly the incidence of postoperative wound infection in patients with a gangrenous or perforated appendix (P less than 0-025). Prophylactic cephaloridine significantly reduced the overall incidence of wound infection (P less than 0-02) and was also effective when the appendix was gangrenous or perforated (P less than 0-01). A highly significant reduction in wound infection was achieved when the appendix was gangrenous or perforated by the addition of wound drainage to the antibiotic regimen (P less than 0-001).