BackgroundDespite complete resection of mature ovarian teratoma, there remains a risk of metachronous contralateral disease with implications for further surgery and fertility. Current estimates of this risk are wide and practice regarding surveillance varies. We aimed to identify the incidence of metachronous contralateral disease in girls presenting with unilateral mature ovarian teratoma and to describe current follow-up.MethodsRetrospective case note review was performed for all girls (< 17 years) undergoing surgery for histologically confirmed mature ovarian teratoma between 1998 and 2018. Data concerning initial hospital episode, follow-up, and further intervention were collected.ResultsForty-five girls were identified with a median age of 10 years (range 1–16). Salpingo-oophorectomy (47%) and oophorectomy (36%) were the commonest operations. Median follow-up was 2 years (range 0–16 years) with surveillance ultrasonography performed in 49%. One case of metachronous contralateral teratoma (2%) was detected at 1 year, requiring oophorectomy and ovarian tissue cryopreservation.ConclusionsThis series has demonstrated a lower incidence of metachronous contralateral mature ovarian teratoma compared to previously published data. Postoperative surveillance is variable, and the true natural history of this condition remains incompletely understood. Prospective, multicentre investigation at national or international level is required to improve the evidence upon which to base safe standards of care.