We have evaluated the efficacy and toxicity of a chemotherapy consisting of methotrexate, mitoxantrone, 5-Fluorouracil and leucovorin in 21 advanced breast cancer patients. Among 20 evaluable patients, objective response was obtained in 6 patients (30%) with two complete responses, stable disease in 4 patients (20%), while 10 patients (50%) progressed. Median progression-free survival and survival were 10 and 15 months, respectively. The most frequently observed side-effects were myelosuppression and emesis; one patient, who had previously received doxorubicin at the maximum dose-limiting cardiac toxicity, died of congestive heart failure after the third cycle. This treatment is moderately effective for advanced breast cancer patients.