Brain metastases are found at diagnosis in 10% of patients with small cell lung cancer. To clarify the effect of central nervous system metastases on prognosis, the records of 429 patients with small cell lung cancer were reviewed. Forty-three patients (10%) presented with brain metastases. In 18 patients the brain was the only site of metastatic disease, whereas the remaining 25 patients had at least one additional metastatic site. Forty-one of forty-three patients were treated with combination chemotherapy and cranial radiotherapy. Systemic response rates were similar for both groups. Twenty-seven patients underwent repeat central nervous system staging: 19 (70%) had a complete response, 4 (15%) a partial response, and 4 (15%) no response. Median survival of patients with only one site of metastatic disease was 11 months; patients with additional sites lived 5 months (p = 0.153). Survival in patients with only one site is similar to that in patients with limited disease (11 compared with 13 months; p = 0.074).