Brain metastases occur frequently and are a significant threat to the quality of life in patients with small cell lung carcinoma. The primary treatment modality has historically been whole brain radiation, which can provide a moderate extension of life and improvement in neurologic symptoms. Despite increasing interest in the use of alternative therapeutic agents-primarily chemotherapy-these have yet to be demonstrated to be superior to radiation in management of brain metastasis. Prophylactic cranial irradiation prevents or delays the occurrence of brain metastases in patients with small cell lung carcinoma. Until recently, this benefit has been thought to be primarily restricted to a minority of patients with limited stage disease. A large European trial, however, has now shown a survival benefit to the use of prophylactic cranial irradiation in patients who have any response to systemic chemotherapy. This finding should significantly shift management practices for this aggressive disease for most patients.