Two policies of palliative thoracic radiotherapy for non-small-cell lung cancer have been compared in a randomised multicentre controlled trial. A total of 369 patients with inoperable, histologically or cytologically confirmed disease, too advanced for radical ‘curative’ radiotherapy, and with their main symptoms related to the primary intrathoracic tumour even if metastases were present, were studied. They were allocated at random either to a regimen of 17 Gy given in two fractions of 8.5 Gy 1 week apart (F2 regimen), or to a conventional multifractionated regimen of either 30 Gy in ten fractions or 27 Gy in six fractions (a biologically equivalent dose), given daily except at weekends (FM regimen). On admission, 93% of the patients had cough, 47% haemoptysis, 57% chest pain, 58% anorexia, and 11% dysphagia. As assessed by the clinicians, palliation of the main symptoms was achieved in high proportions of patients ranging in the F2 group from 65% for cough to 81% for haemoptysis and in the FM group from 56% for cough to 86% for haemoptysis. Haemoptysis, chest pain, and anorexia disappeared for a time in well over half the patients with these symptoms, and cough in 37%. For all the main symptoms, the median duration of palliation was 50% or more of survival. Performance status improved in approximately half of the patients with a poor status on admission. All these results were similar in the two treatment groups. As assessed daily by the patients using a diary card, the quality of life deteriorated slightly during treatment but then improved steadily during the next 5 weeks. The proportion of patients with dysphagia increased considerably during treatment, but fell to the pretreatment level during the next 2 weeks. The results were similar in the two groups. Radiation myelopathy was suspected in one (F2) patient. There was no difference in survival between the two groups (log-rank test), the median survival time from the date of allocation being 179 days in the F2 and 177 days in the FM group. In the light of all the findings, the regimen of two fractions of 8.5 Gy given 1 week apart is recommended.