The purpose of this investigation was to explore the potential benefit of hormone therapy in addition to external beam radiotherapy for patients with early-stage (T1-2), intermediate-(prostate-specific antigen [PSA] > 10 or Gleason score >or= 7) or high-risk (PSA > 10 and Gleason score >or= 7) prostate cancer. The charts of 412 patients with early-stage intermediate- and high-risk prostate cancer treated with external beam radiotherapy with or without a 4-month total androgen blockade were reviewed. The groups were balanced with respect to age, pretreatment PSA, and stage, but differed with respect to Gleason score and radiation dose. Biochemical failure rates, as defined by the ASTRO consensus panel, were compared between those receiving and those not receiving hormones. With a median follow-up of 2.0 years, the biochemical failure rate was 12.1 versus 23.1% (p = 0.02) in favor of those receiving hormones. This difference was seen for the subgroups followed for more than 6 months (12.5 vs. 25.0%), more than 9 months (14.5 vs. 26.3%), and more than 12 months (17.3 vs. 27.0%). Thus, biochemical failure decreased with the administration of hormone therapy in this group of patients with early stage, intermediate- or high-risk prostate cancer. This finding requires validation by ongoing randomized trials.