1. The results of a detailed analysis of 137 cases of elderly patients with bladder cancer, treated by supervoltage therapy, are presented. 2. The 5 year actuarial survival rates were 17 per cent for the entire series, 28 per cent for Group 1, 19 per cent for Group II, 0 per cent for Group III (Stage D), 33 per cent for Stage OAB1, and 13 per cent for Stage B2C. Nearly all recurrences occurred before 3 years after therapy. 3. Thirty-one per cent of the patients died of other causes with or without the recurrence of cancer. In the class of patients who died of other causes with recurrence, only 4 of the 19 patients required definitive treatments for their recurrences. 4. The analysis of clinical data in terms of recurrence-free and survival rates, as well as of the causes of death, is a better method of assessment of results in the treatment of bladder cancer than in terms of survival rates alone. 5. The importance of the undertaking of clinical trials for the comparison of results of two or more methods of treatment is emphasized. 6. The further analysis of retrospective data from large populations of bladder cancer patients by modern statistical methods may yield further information about the classification and prognosis of bladder cancer than possible by routine statistical methods.