Thirty-eight patients with malignant mesothelioma of the pleura were seen at Peter MacCallum Cancer Institute between 1981 and 1985. In 35 patients presenting with disease confined to one hemithorax, the following treatments were given: radical surgery, 13 patients: radical radiotherapy, 12 patients; palliative radiotherapy, 20 patients; chemotherapy, 9 patients; observation only, 2 patients. Median survival from time of diagnosis for all 38 patients was 9 months, with an estimated 2-year survival rate of 16%. Treatment did not significantly affect survival, although there was an indication that patients having radical surgery did better (median survival 17 months) than those who did not (median survival 9 months) (p = 0.13). Fifteen patients were given radiotherapy with radical intent but only 12 completed treatment (50 Gy). The median survival of the 12 patients completing radiotherapy was 17 months, with an estimated 2-year survival rate of 17%. Two patient deaths were attributable to radical radiotherapy (one radiation hepatitis, one radiation myelopathy). Twenty-one patients received 31 courses of palliative radiotherapy for various symptoms, predominantly pain. The results were assessable for 26 courses, with 17 (65%) being at least partly successful. In conclusion, radiotherapy appears to be ineffective in prolonging survival in malignant mesothelioma of the pleura, but has a useful role in palliation.