Twenty previously untreated patients with small cell carcinoma of the lung were treated with cyclophosphamide, 400 mg/m2 and Adriamycin, 40 mg/m2 IV on day 1, followed by cytosine arabinoside, 20 mg/m2, every 12 hours subcutaneously on days 5--9; this regimen was repeated every 28 days. On days 14--28 of the first cycle, each patient received 3,000 rads to the primary tumor and whole brain. Following eleven courses, Adriamycin was discontinued and patients received cyclophosphamide, 800 mg/m2 IV on day 1 and methotrexate, 15 mg/m2 IV on days 5--7. This regimen was repeated every 28 days. Toxicity included nausea, vomiting, alopecia, leukopenia, thrombocytopenia, and esophagitis. Overall response rate was 65%. Media survival in limited disease was 14.5 months, and in extended disease it was 4.5 months. This combination is active in localized small cell carcinoma but provides no superiority over other regimens.