We have treated 10 patients with small-cell carcinoma of the lung with an aggressive weekly chemotherapy regimen. Treatment consisted of cyclophosphamide and doxorubicin (Adriamycin) on day 1, methotrexate on day 8, followed by leucovorin on days 9, 10, and 11 cis-platinum on day 15, VP-16 on days 15, 16, and 17, vincristine on days 1, 8, 15, and 22, and trimethoprim/sulfa twice daily. Cycles were repeated every 28 days. The primary toxicity was hematologic. One treatment-related death occurred. All other patients tolerated treatment without irreversible toxicity. There have been three complete responses and seven partial responses. This very active regimen is tolerated with acceptable toxicity even in patients with poor performance status.