The long-term outcome for 1,245 patients with carcinoma of the prostate treated with external beam radiation therapy is presented. The median survival for all patients without evidence of distant metastases but irrespective of T stage of the primary tumor, histopathological grade or lymph node status was 10 years compared to 15 years for an age-matched cohort of California men. The cause specific survival at 15 years was 52%. The data base is subdivided into a series of subsets that demonstrate the impact of T stage, Gleason pattern score and lymph node involvement on long-term outcome. The best results were shown in stages T1 and T2a cases with histopathologically proved negative lymph nodes. Survival at 15 years was 53%, which was essentially identical to the 55% survival rate of an age-matched cohort. The actuarial survival at 15 years for all stages T1 and T2N0M0 cancer patients was 45% compared to 56% for an age-matched cohort.