Heavy menstrual bleeding (HMB) is a common complaint among adolescent girls. It reflects an abnormal volume of blood loss during the menstrual cycle. Abnormal uterine bleeding can manifest as HMB but includes menstrual irregularity. In many cases, immaturity of the hypothalamic-pituitary-ovarian axis or hormonal conditions like polycystic ovarian syndrome leading to anovulatory cycles are the underlying cause for heavy menses. However, in girls with HMB, especially those not responding to the usual hormonal attempts to manage HMB, an underlying bleeding disorder should be considered. Up to 62% of adolescents with HMB have a bleeding disorder, many without anemia at presentation. Evaluation for HMB in an adolescent girl should include referrals to an adolescent medicine specialist or gynecologist and pediatric hematologist. [ Pediatr Ann . 2020;49(4):e163–e169.]