Aim: Effect of replacing open drainage system to closed drainage system on surgical site infection (551) in children operated for perforated appendicitis was evaluated. Material and Method: Hospital files and computer records of perforated appendicitis cases operated in 2004-2010 were evaluated retrospectively. Open drainage systems were used for 70 in cases (group I) and closed systems were used in the others (group II). Results: Eleven of 551 cases had superficial infection and 3 had the organ/space infection. 551 rate was 15.795 for group I and 7.59'n for the group II. The antibiotic treatment length was 7.5 t 3.4 days for group I and 6.4 2.2 days for group II and the difference between groups was not statistically significant. Hospitalization length for group I was 8.2 3.1 days and 6.8 1.9 days for group II and the difference was statistically significant. Discussion: 551 is an important problem increasing morbidity and treatment costs through increasing hospitalization and antibiotic treatment length. Open drainage system used in operation in patients with perforated appendicitis leads an increased frequency of SSI when compared to the closed drainage system. Thus, closed drainage systems should be preferred in when drainage is necessary in operations for perforated appendicitis in children.