The prognosis of stage III non-small cell lung cancer (NSCLC) can be improved by a combination of radiotherapy (RT) and chemotherapy (CT). In this study, the GOTHA group evaluated the feasibility, tolerance, tumour response, pattern of failure and effect on survival of a combination alternating accelerated hyperfractionated (AH) RT and CT in patients with tumour stage III NSCLC. 65 patients received 3 cycles of cisplatin 60 mg/m2 and mitomycin C 8 mg/m2 on day 1, and vindesin 3 mg/m2 on days 1 and 8 in weeks 1-2, 5-6 and 9-10, alternating with AHRT, 2 daily 1.5 Gy fractions, 5 days/week, in weeks 2-3 (30 Gy) and weeks 6-7 (33 Gy). The dose actually delivered was > 98% for RT, and 85-100% for CT. Mean duration before last CT cycle was 9.5 weeks. Toxic effects were leucopenia, nausea and vomiting, mucositis, diarrhoea, alopecia and peripheral neuropathy. 1 patient died of bronchial haemorrhage at the end of RT. 1 of 5 patients, who underwent secondary pulmonary resections, died of acute respiratory distress syndrome. Evaluation of tumour response was hampered by lung condensations in radiation fields. Some long-term survivors had an initial tumour response assessed as partial response or no change. First failures were more frequent outside (34) than within (21) radiation fields. The median survival was 15.7 months and the 5 year survival rate was 15% (95% CI = 6-26%). 1 patient died of bladder cancer and another of myocardial infarction. Alternating CT and AHRT, as used in this study, were well tolerated and allowed full dose delivery within less than 12 weeks. Initial response was not predictive of survival. The survival curve is encouraging and the 5 year survival is superior to the 5% generally observed with conventionally fractionated radiotherapy.