Twenty-five patients were treated on a Phase II study of doxorubicin, 60-75 mg/m2 intravenously every 3 weeks, accompanied by metronidazole, 1500 mg/m2 orally 12 hours and immediately before the doxorubicin and 6 hours and 24 hours after the doxorubicin. Of 23 patients evaluable for response, 2 (9%) achieved complete remissions, 2 (9%) achieved partial remissions, and 4 (18%) were stable (one of whom achieved a minor response). One patient with an inoperable biopsy-proven 4 x 3 x 3 cm recurrence following radiation and surgery has had a complete remission that persists at 8 years. The second patient who achieved a complete remission subsequently underwent surgical resection of the involved area. No residual tumor was found, and he remains disease free after 8.5 years. Doxorubicin toxicity did not appear to be augmented significantly by metronidazole. Although the response rate seen in this study was low, the occurrence of two long-term complete remissions suggests that this combination should be studied further in other tumor types.