In a 3-year study, 103 children with acute non-perforated appendicitis who underwent appendicectomy were randomized for either a single preoperative dose of gentamicin and metronidazole or three doses of gentamicin and metronidazole given before and after the operation. The overall wound infection rate was 1.9%. There was no significant difference between wound infection rates of the single-dose group (2.1%) and the three-dose group (1.8%). The mean(s.d.) hospital stays of the single-dose and three-dose groups were similar: 6.6(2.2) days and 6.4(2.7) days. This study shows that a single preoperative dose of gentamicin and metronidazole is as effective as three doses of gentamicin and metronidazole in the control of post-appendicectomy wound sepsis.