Antibiotic administration during acute appendicitis in children continues to be debated. The purpose of this study was to compare efficacy of two prophylactic antibiotic treatment guidelines in acute appendicitis and peritonitis in children. The infectious complication rate after appendicectomy was compared during two distinct periods (before/after study). During the first period, the guidelines for antibiotic administration were based on ticarcillin-clavulanic acid. During the second period, the guidelines were based on amoxicillin-clavulanic acid for non-perforated appendicitis or appendicitis with localized peritonitis, and clavulanic acid was reserved for general peritonitis. All children younger than 16 years of age who underwent appendicectomy during the periods studied were included. Data were retrospectively collected from surgical and anesthetics charts. Ninety-five children during the first period and 238 during the second were included. In the children with non-perforated appendicitis, no postoperative infectious complication occurred in 74 children during the first period versus two out of 153 (1%) during the second period. In cases of perforated appendicitis, postoperative infectious complications occurred two cases (10%) during the first period versus nine (11%) during the second. There were no significant differences between the two periods. In this population, antibiotic administration guidelines based on amoxicillin-clavulanic acid for stages I-III of appendicitis maintained a low rate of postoperative infectious complications and were not associated with a higher postoperative infectious complication rate than guidelines based on ticarcillin-clavulanic acid.