During a 14-year period, 500 consecutive patients having localized prostate cancer were treated with external beam radiotherapy with curative intent. Patients were staged according to the Whitmore-Jewett and TNM systems. Median follow-up for all patients was 69 months. Local recurrence included failures detected by rectal examination and/or prostate biopsy. Progressively elevated prostate-specific antigen (PSA) values at follow-up with no evidence of systemic disease also was considered a local treatment failure. Overall 5- and 10-year survival rates were 65% and 37%, respectively. Cause-specific 5- and 10-year survival rates were 79% and 55%, respectively. Five- and 10-year local control rates for all patients were 72% and 52%, respectively. No patient with a T1 a tumor failed locally. When follow-up PSA data were included in control criteria, 10-year local control rates for patients with T1b, T2a, and T2b-T4 tumors were 66%, 55% and 44%, respectively. If only an abnormal rectal examination and/or a positive post-treatment biopsy was considered as evidence of local failure, control rates were significantly better. Approximately one third of the study patients had died of cancer or intercurrent disease before the PSA test was used routinely. Of the 244 patients (49%) for whom follow-up PSA values were available, 116 had a normal post-treatment PSA with no evidence of disease; 94 were alive and 22 died with no evidence of prostate cancer.(ABSTRACT TRUNCATED AT 250 WORDS)