Brain metastases are common in patients with small cell lung cancer (SCLC), and prophylactic cranial irradiation (PCI) has been shown to reduce the risk of brain metastases in these patients. But how great are the benefits, and do the benefits outweigh the toxicity? In this month's Counterpoints, Dr Ben J. Slotman makes the case for the use of PCI in nearly all patients with SCLC who have responded to treatment, whereas Jacob Yousef and Dr Henry Wagner argue that the role of PCI should be reassessed.