Twenty-two patients who had received high-dose radiotherapy (50-60 Gy) for non-small-cell lung cancer were retreated with palliative radiotherapy for symptoms that were due to locally recurrent disease. Twelve of the 23 (one patient was retreated twice) repeat courses produced symptomatic benefit. One patient developed spinal-cord injury after retreatment, but this was probably not related to the second course. There were no other serious complications, even though total tumour doses as high as 120 Gy were achieved. This experience demonstrates that repeated courses of radiotherapy can be given successfully and safely in spite of previous radical dosage.