Forty-six eligible patients with metastatic breast cancer (MBC) were treated with a combination of methotrexate, vinblastine, doxorubicin, and cisplatin (M-VAC) as first-line chemotherapy. Of 44 patients evaluable for response, 28 (64%) had an objective response, including seven (16%) who had a complete response. The median duration of response was 4 months (range, 0 to 38 months), and the median survival from the time of entry was 14 months (range, less than 1 to greater than 45 months). Myelosuppression was the most common dose-limiting toxicity, with 54% of patients experiencing Grade 3 or 4 leukopenia (including 28% with granulocytopenic fever and one septic death), and cumulative Grade 3 anemia occurred in 28% of patients. Grades 3 to 4 stomatitis was observed in 18% of patients. An active, although highly toxic regimen when used as first-line therapy in MBC, M-VAC has a response rate and survival duration similar to existing, less toxic combination regimens. As such, M-VAC cannot be recommended in preference to other combination chemotherapy regimens in this clinical setting.