Over 50% of patients with small cell lung cancer (SCLC) will develop symptomatic brain metastases during the course of their disease. Results of whole brain radiotherapy, the standard treatment, are rather poor and relapses are frequent. Thus, new modes of therapy are urgently needed for these patients. In this study, the efficacy of teniposide was evaluated at a dose of 150 mg/m2 intravenously on days 1, 3, and 5 at 3-week intervals. In 11 of 26 evaluable patients an intracranial response was observed. Median response duration was 23 weeks (range, 9 to 50). Toxicity was acceptable, with grades 3/4 leukocytopenia and thrombocytopenia reported in 37% and 16%, respectively, of 123 courses. Therefore, teniposide is an effective agent against brain metastases of SCLC and is suitable for palliation of these patients.