Pelvic tumors in adolescent females are very uncommon. While the most common presentation is pelvic discomfort, we report the case of a 14-year-old female presenting with menorrhagia which is an unusual initial complaint for a large pelvic tumor. Adolescent females who present with heavy menstrual bleeding initially undergo assessment to rule out a bleeding disorder. In this case, careful history and physical examination helped in making a quick diagnosis and management. Ultrasound of abdomen showed a huge cystic mass due to serous cystadenoma of the ovary.