Sixty-seven patients with advanced breast cancer were prospectively entered into a Phase II trial of cyclophosphamide 100 mg/m2 orally on days 1-14, methotrexate 40 mg/m2 intravenously (i.v.) on day 1, 5-fluorouracil 600 mg/m2 i.v. on day 1, and prednisolone 40 mg/m2 orally on days 1-14 (CMFP) rapidly alternating with doxorubicin 25-30 mg/m2 i.v. on day 8 and vincristine 1.4 mg/m2 i.v. on day 8 (AV). Complete responses (CR) were seen in 7 patients, partial responses (PR) in 25 (CR + PR, 48%), stable disease in 24, and progressive disease in 9. The median time to disease progression was 9.8 months, and the median survival 19.4 months. Neutropenia was the major toxicity with WHO grade 3 or 4 neutropenia in 50% of patients. CMFP/AV is a well-tolerated, effective regimen in advanced breast cancer but does not appear to be superior to CMFP alone.