From 1974 to 1987, a total of 199 patients with prostatic carcinoma localized to the pelvis were treated with definitive external beam radiation therapy at the Istituto Medico e di Ricerca Scientifica. The median follow-up for all 126 surviving patients was 60 months. Actuarial 5-(and 10-) year overall survival rates for U.I.C.C. clinical Stage T1-2, T3 and T4 disease were 76.1% (58.5), 66% (42.5), and 27.6%, respectively. The corresponding 5- and 10-) year disease-specific survival rates were 81.7% (73), 72.5% (57.4), and 36.2%. The corresponding values of disease-free survival were 81.3% (76.8), 59.2% (57), and 17%, respectively. In 120 patients with more than 5 years of follow-up, local failure was seen alone in eight patients (6.6%) and associated with distant metastases in 19 patients (15.8%). In 28 patient (23.3%), distant metastases were observed alone. The median survival from the first evidence of metastases was 20 months, with no patient surviving beyond 5 years. The incidence of complications was acceptable. Serious complications, consisting of stenosis of both ureters and sigmoid colon requiring both urinary and intestinal diversion, occurred in two patients (1.3%). This study reveals that external radiotherapy is an efficacious and safe modality for locoregional control of prostate cancer.