Background To compare the risk of complications between initial nonoperative treatment and appendectomy of uncomplicated (simple) appendicitis in children. Methods Systematic literature search. Eligible for inclusion were both and randomized controlled trials and cohort studies including children in which the outcome of nonoperative treatment of uncomplicated appendicitis was reported with a minimum follow-up period of one year. Two authors extracted data independently and assessed quality. Primary outcome parameter was the percentage of children experiencing complications. Secondary outcomes were early failures, recurrent appendicitis and appendectomies, for all indications and on request. Results Five of the 2051 articles screened were eligible for inclusion, including 147 children (nonoperative treatment) and 173 children (appendectomy) with one year follow-up. Percentage of children experiencing complications ranged from 0 to 13% versus 0–17% for nonoperative and appendectomy, respectively. Nonoperative treatment avoided an appendectomy in 62–81% of the children after one year follow-up. Conclusion The evidence base for initial nonoperative treatment of acute uncomplicated appendicitis in children is by far insufficient. It suggests that the percentage of patients experiencing complications in the initial nonoperative treatment group is comparable to the appendectomy group, and it may avoid an appendectomy in the large majority of children after one year follow-up. Type of study Systematic review. Level of evidence 1.