Thirty-two patients with metastatic breast cancer who had not received prior chemotherapy for metastatic disease were entered into a trial of mitoxantrone 12 mg/m2 plus cyclophosphamide 600 mg/m2 given at three weekly intervals. Thirty-one patients are eligible for assessment. Response was seen in 65% (4/31 complete regression; 16/31 partial regression). Median duration of response was 6 months and median duration of survival was 10 months. Mitoxantrone + cyclophosphamide appears to be an active combination in treatment of metastatic breast cancer.