Between January 1985 and June 1991, 19 patients, in whom the site and extension of the tumour prevented surgical excision, were treated with high dose radiotherapy as sole treatment for high grade astrocytomas. Quality of life, according to functional capacity, was measured prospectively before treatment and 4 weeks later. High dose radiation improved the functional capacity in only four of the patients (21%). The mean duration of improvement was 12 weeks and median survival 22 weeks (range 4-80). We conclude that high dose radiotherapy is not very useful and is probably not justified in this group of patients.