An aggressive variant of adenosarcoma, mullerian adenosarcoma with sarcomatous overgrowth (MASO) in the cervix is extremely rare. This variant contains obvious, high-grade sarcoma in addition to a low-grade form. In this report, we describe a case of MASO of the uterine cervix and review the clinical and pathological features of these tumors. The patient was a 37-year-old woman with a cervical polypoid mass, which was morphologically considered as a benign endocervical polyp. Microscopically, polypoid cervical mass showed diffuse and dense malignant spindle cell proliferation around the benign endocervical glands and also an area of markedly anaplastic and pleomorphic spindle cell proliferation, so called, sarcomatous overgrowth. Total abdominal hysterectomy and bilateral salpingo-oophorectomy with pelvic lymph node dissection were performed. The patient has been followed-up and neither chemotherapy nor other adjuvant therapies have been administered. At present, she has been clinically free of disease for 9 months since she received surgery. It is extremely rare that MASO of the uterine cervix is presented in premenopausal woman. Gynecologists and pathologists should be aware of the difficulties associated with a delay in the diagnosis of MASO when the tumor is present as a benign looking cervical polyp.