Fourteen patients with small cell lung cancer were treated with cisplatin (80 mg/m2 i.v.) and etoposide (300, 400, 500 mg/m2 i.v.). This combination chemotherapy was administered over a three- or four-week period. Eleven of 13 evaluable patients showed a greater than 50% tumor reduction, but there were 3 complete responses and 5 partial responses, giving a response rate of 61%. Four patients who were initially treated achieved major responses. In 9 patients who had received prior chemotherapy, 4 achieved a major response. Of 3 complete responders, 2 patients had previously received etoposide treatment alone. The renal toxicity of this regimen was minimal and no patients developed any clinical symptoms. Nausea and vomiting were well controlled by high-dose metoclopramide and methylprednisolone. All patients, however, experienced appetite loss after treatment. The dose-limiting toxic effect of this regimen was hematologic toxicity. We therefore concluded that the combination of etoposide (300 mg/m2 i.v.) and cisplatin (80 mg/m2 i.v.) is repeatable at 3 or 4 week intervals and effective in patients with small cell lung cancer.