Bilateral adnexal tumors detected during her regular ultrasonography (US) examination. A 16-year-old girl (G0P0) presented to our gynecology department at Chonnam National University Hospital with bilateral adnexal tumors detected during her regular US follow-up. She had undergone bilateral ovarian cystectomy for mature teratomas at our hospital 3 years ago and was under regular 6-month follow-up at a local gynecology center. Her mother, maternal aunt, and maternal grandmother had undergone surgeries for mature ovarian teratomas. She was systemically healthy. Her vital sign was stable. Non-specific sign was showed on physical examination. Her laboratory findings were normal. The tumor markers, α-fetoprotein and β-human chorionic gonadotropin were within normal range. Subsequent pelvic magnetic resonance imaging (MRI) showed multiple cystic masses in the left ovary and multiple cystic masses in the right ovary, which strongly indicated recurrent mature cystic teratomas.