From 1974 through 1982, 286 patients with histologically proven bladder cancer (Tis 8, T1 62, T2 109, T3 86, T4 21 NXMO) were treated with external irradiation after transurethral resection. Irradiation was given with 260 degrees arc technique photon beam from a Cobalt Unit; the tumor doses ranged from 52.5 to 65 Gy in 21-50 days, with a TDF between 75 and 110. The analysis was conducted with the log rank test on the cumulative percent survival (CPS) at 5 years. The study pointed out the importance of risk factors other than clinical stage on cumulative survival in bladder cancer. Prognostic factors associated with a relatively successful outcome (p less than 0.001) were the Karnofsky performance status (100 vs others) (CPS 75% vs 30%), the absence of ureteral obstruction on the initial intravenous pyelogram (CPS 50% vs 35%), a negative urine culture (CPS 60% vs 30%), normal bladder capacity (CPS 50% vs 35%), low-grade histology (CPS 65% vs 35%), and grossly complete resection (55% vs 40%). The data from this analysis should be taken into consideration when radical radiotherapy is considered in new clinical trials.