Preoperative prophylaxis with metronidazole suppositorium to patients undergoing appendectomy was introduced in our department in 1981. One hundred consecutive patients who had an appendectomy in the period May to October 1988 were reviewed to assess the efficiency of the prophylaxis. Postoperative infections were found in seven cases, but none were serious or caused sequelae. The clinical results of this simple, low-cost practice are satisfying, and we therefore intend to continue using metronidazole suppositorium as prophylaxis before appendectomy.