The case records of 116 patients treated with radical megavoltage X-ray therapy for carcinoma of the prostate have been reviewed. The age-corrected actuarial 5-year survival rate was 60.0% and the 10-year rate was 31.5%. Multivariate analysis demonstrated that T classification was the strongest prognostic variable but a long delay between diagnosis and radiotherapy also had a detrimental effect on prognosis. The incidence of severe acute and late radiation morbidity was low. Radical radiotherapy has been shown to be a safe and effective form of management for localised carcinoma of the prostate.