Abstract Forty-three patients with metastatic breast cancer were treated with a total of 385 cycles of combination chemotherapy consisting of adriamycin, cyclophosphamide, 5-fluorouracil, methotrexate and vincristine sulphate given over 24 hr and followed by a leucovorin ‘rescue’. Thirty patients (70%) responded with three complete remissions. Thirteen patients did not respond, including six in whom the progression of disease was apparently arrested. Duration of response ranged from 2 to 24 months. At 20 months, 10 of 30 responding patients were alive compared with 1 of 13 non-responders. Toxicity was minimal apart from nausea and vomiting. This study confirms previous reports that intensive chemotherapy can be given safely over 24 hr without loss of therapeutic effect. This regimen is now being tested as an adjuvant to mastectomy in node-positive operable breast cancer.