To investigate the clinicopathologic features, diagnosis, treatment and prognosis of uterine mullerian adenosarcoma.The clinicopathological data of 9 cases of uterine mullerian adenosarcoma in PUMC hospital from January 2003 to February 2009 were retrospectively analyzed.There were 6 uterine endometrial adenosarcomas and 3 cervical adenosarcomas. The main clinical manifestations were abnormal vaginal bleeding and pelvic pain. Physical examination showed cervical/vaginal mass, enlarged uterus or pelvic mass. The adenosarcoma was characterized by benign or atypical-appearing neoplastic glands within a sarcomatous stroma. This stroma could appear as periglandular cuffs or intraglandular polypoid projections of increased cellular structure. The primary diagnostic rate was 66.7% and the most common clinical stage was stage I (7/9). All patients received surgical treatment and seven had postoperative chemotherapy, radiotherapy or hormone therapy. Conservation of unilateral ovary or bilateral ovaries was performed in 5 cases. Three patients underwent local excision, which resulted in the preservation of reproductive function. During the follow-up, 2 cases of uterine endometrial adenosarcoma recurred. One patient of clinical stage III containing sarcomatous overgrowth died from recurrence 13 months after surgery. The other one recurred 2 years after local excision of the tumor in the uterine cavity and she remained healthy since hysterectomy.Uterine mullerian adenosarcoma is a rare tumor without specific clinical symptoms and signs. The diagnosis depends on pathomorphologic examination. The tumors show low malignant potential and the vast majority are at early stage. Surgical excision is the main treatment strategy with a good prognosis in the early stage disease with complete removal of tumors. The prognosis is poor in advanced adenosarcoma with sarcomatous overgrowth. Due to the relatively high rate of recurrence, long-term follow-up is recommended.