Epithelial ovarian cancer is the most common cause of death due to gynecologic malignancies in adults, but is rare in children and adolescents. The majority of ovarian cancers in children and adolescents are stage I at diagnosis and conservative management with preservation of fertility is often possible. Twenty-nine serous epithelial cancers have been reported in females under age 20, only two of which are known to be advanced stage (both stage III). We present a case of advanced stage papillary serous cystadenocarcinoma in a 15-year-old female treated with bilateral salpingo-oophorectomy and debulking surgery followed by combination chemotherapy.