Objective Ovarian mature teratoma (OMT) is a common ovarian tumor found in the pediatric population. In 10% to 20% of cases, OMT occurs as multiple synchronous or metachronous lesions on ipsi- or contralateral ovaries. Ovarian sparing surgery (OSS) is recommended to preserve fertility, but total oophorectomy (TO) is still performed. This study reviews the clinical data of patients with OMT, and analyzes risk factors for second events. Design A retrospective review of all girls under 18 years of age with OMTs was performed. Data on clinical features, imaging, laboratory studies, surgical reports, follow-up second events and their management were retrieved. Results Overall, 350 children were identified. Eighteen patients (5%) presented with a synchronous bilateral form at diagnosis. Surgery was performed by laparotomy (85%) and laparoscopy (15%). OSS and TO were performed in 59% and 41% of cases respectively. Perioperative tumor rupture occurred in 23 cases, independently of the surgical approach. Twenty-nine second events occurred (8.3%) in a median time of 30.5 months from diagnosis (ipsilateral: 8 cases including one malignant tumor, contralateral: 18 cases, both ovaries: 3 cases). A large palpable mass, bilateral forms at diagnosis and perioperative rupture had a statistical impact on the risk of second event, whereas type of surgery or approach did not. Conclusion This study is a plea in favor of OSS as the first choice of treatment of OMT when possible. Close follow-up during the first five years is mandatory considering the risk of 8.3% of second events especially in cases with risk factors.