BACKGROUND The role of surgical cytoreduction and combination chemotherapy for malignant mixed müllerian tumors (MMMT) of the ovary was evaluated. METHODS A retrospective review of 27 women with ovarian MMMT treated from 1980 to 1990 was performed. RESULTS The International Federation of Gynecology and Obstetrics stages for the 27 women were 1 Stage I, 3 Stage II, 17 Stage III, and 6 Stage IV. Only 10 of the 23 patients with Stage III or IV disease were cytoreduced optimally. With respect to postoperative therapy, 3 women received no treatment, 6 were treated with whole abdomen radiotherapy, 1 received melphalan, and 17 received chemotherapy incorporating a platinum agent (3), doxorubicin (4), or both (10). The significant prognostic factors were stage (P < 0.001) and, for women with Stage III or IV disease, the feasibility of cytoreductive surgery (P = 0.03). The four patients in Stages I or II remained disease free after an interval of at least 5 years. The median and 5-year survival rates for patients with Stages III or IV disease was 18 months and 8%, respectively. Patients in Stage III or IV for whom optimal cytoreduction was not possible had a 2-year survival of 14%, whereas optimal cytoreduction was associated with a 52% 2-year survival. Median survival for the 14 women with Stage III or IV ovarian MMMT treated with combination chemotherapy was 25 months and nine women achieved progression free intervals of greater than 18 months. CONCLUSIONS Aggressive surgical cytoreduction followed by combination chemotherapy may result in improved progression free intervals for women with advanced ovarian MMMT. However, a major improvement in prognosis for this rare malignancy has not yet been achieved.