A number of retrospective and randomized trials have studied the effect of external-beam radiation therapy (EBRT) plus androgen deprivation therapy (ADT) on locally advanced/high-risk prostate cancer. Of 6 published randomized trials that have compared EBRT plus ADT with EBRT alone, 2 have shown a highly significant overall survival benefit for EBRT plus ADT, and 2 have demonstrated an advantage for the combination in patient subsets based on Gleason score. The results from the positive trials of EBRT plus ADT versus EBRT alone, as well as a recent report of a comparison of short-term (6 months) ADT plus EBRT versus long-term (>6 months) ADT plus EBRT, suggest that short-term ADT plus EBRT preferentially lengthens the survival of patients with Gleason score 2 to 6 disease, whereas for Gleason score 8 to 10 disease, prolongation of survival requires long-term ADT plus EBRT. These data are far from clear-cut because there are factors that confound interpretation of the subgroup analyses. Retrospective data on patients with positive lymph node status support the assertion that EBRT plus ADT prolongs survival to a greater degree than either treatment given individually. The weight of the available investigations on the survival effect of EBRT plus ADT supports its use on a routine basis for patients with high-risk prostate cancer. The results with long-term ADT are much more convincing than short-term ADT, and, as a consequence, 2 to 3 years are recommended.