Recent developments in the urologic oncology literature suggest that residual local disease--as opposed to the presence of occult metastases at surgery--may characterize a more substantial component of the natural history of the recurrence and progression of initially clinically localized prostate cancer than previously appreciated. These important studies have illuminated the extent to which postoperative radiotherapy (RT) may provide benefit to patients with adverse pathologic features (extraprostatic extension, seminal vesicle invasion, or positive surgical margins) or biochemical recurrence after radical prostatectomy. Nevertheless, the question of whether all patients with the aforementioned adverse features should undergo immediate adjuvant RT versus initial observation with more selective--but early--salvage RT in the event of biochemical failure remains the subject of heated controversy. This article reviews salient recent studies in this field to address important questions relevant to counseling patients on the use of postprostatectomy RT. Discussion points include data supporting benefit (efficacy), questions of generalizability of benefit (effectiveness) and risks, and important questions for further study.