Uterine leiomyomas are rare in the paediatric population. This report describes a rare case of a submucous leiomyoma in an adolescent girl. The patient presented with a history of abnormal and painful period which was refractory to medical treatment. Sonographic findings revealed a uterine mass that protruded through the cervix until the upper third of the vagina. A hysteroscopic resection was performed, and a pathological examination confirmed a leiomyoma. 12 months after surgery, there were no signs of recurrence. Conservative sparing-fertility management, such as hysteroscopic resection, is the best option with a type 0 submucosal fibroid, especially in adolescents and young women.