Two cases of unresectable retroperitoneal malignant fibrous histiocytoma (MFH) achieving a prolonged complete remission by a combination of chemotherapy (adriamycin plus cyclophosphamide) and abdominal irradiation are reported. Although an optimal treatment policy for such cases has not been established, on the basis of data currently available, chemotherapy regimens including anthracyclines seem the most reliable therapeutic approach in unresectable and/or metastatic MFH.