We retrospectively analyzed the charts of 58 long-term survivors of small-cell lung cancer (SCLC) (greater than 2 years) for neurological complications and their impact on the well-being of these patients. We also attempted to have patients complete a questionnaire regarding any possible neurological problems. This was done in 14 patients. Metastasis to the CNS occurred significantly less often in patients who received prophylactic cranial irradiation (PCI) in a dose of 20 Gy in five equal fractions (two of 48), compared with patients who did not receive it (four of 10) (P less than .006). Delayed neurological complications occurred in nine of 48 (19%) patients who received PCI. However, in only two patients did PCI appear to be responsible for progressive dementia. In the other seven patients (one with weakness in the arms and legs, one with transient left hemiparesis, two with hearing loss, and three with various visual disturbances), chemotherapeutic agents (mainly cisplatin and vincristine) and underlying diseases probably contributed significantly to the occurrence of these complications. In addition, these neurological disturbances were transient or ran a stable course and did not adversely affect the daily life of these patients. In comparison, amongst the 10 patients who did not receive PCI one had progressive dementia and another had hemiparesis secondary to probable brain embolism. We conclude that the use of PCI in these doses was effective in reducing the frequency of CNS metastases and had an adverse effect on the daily life and well-being only in a minority of the patients. Until results of controlled randomized studies show otherwise, PCI should continue to be used as a part of the combined modality treatment of completely responding patients with limited SCLC.