Introduction: Uterine adenosarcoma mostly seen in elderly and there are limited data on appropriate approach in premenopausal patient and the accurate prognosis. Herein we aimed to present a young case of Müllerian adenosarcoma of uterus which had only 9 years old. Case report: A 9year old pre pubertal girl presented to the gynecology department of Isfahan University of Medical Sciences-Iran with the vaginal bleeding. An intrauterine mass was noted via hysteroscopic examination as the reason of abnormal bleeding. The final pathology revealed Müllerian adenosarcoma of uterus. Subsequently hysterectomy was done due to persistent perfused vaginal bleeding; with ovarian preservation. Conclusion: Due to rarity of Müllerian adenosarcoma, the gynecologists and pathologists should be reminded about the possibility of the diagnosis in young patients too.