Malignant mixed müllerian tumor of the fallopian tube is extremely rare, with less than 50 cases recorded in the English literature. Another case is reported and discussed. This 66-year-old female patient complained of profuse watery vaginal discharge for one month. Vaginal cytology was positive for malignancy while the endometrial curettage and cervical biopsy were both negative. Gynecologic sonography revealed a left adnexal mass of 6 cm in diameter. She underwent exploratory laparotomy after complete oncologic survey. The main tumor was confined to one tube but the peritoneal washing cytology was positive for adenocarcinoma cells. She tolerated the maximal debulking surgery very well but refused to receive adjuvant chemotherapy. Pathology proved that the tumor was composed of poorly differentiated adenocarcinoma and sarcoma. There were focal areas of rhabdomyoblastic differentiation with cross striation in immunoperoxidase stain. Carcinomatosis peritonii occurred 12 months after primary surgery and she expired one month later.