Objectives. To evaluate the efficacy and toxicity of three-dimensional conformal radiotherapy (3D-CRT) in the adjuvant and salvage setting after radical prostatectomy (RP). Methods. From 1986 to 1997, 38 patients received adjuvant 3D-CRT, with a median time from RP to 3D-CRT of 2.8 months, and 57 patients were treated with salvage RT for a rising prostate-specific antigen with a median time to 3D-CRT of 27.7 months. The median radiation dose was 64.8 Gy. The median follow-up from completion of RT was 7.0 years (range 1.0 to 14.2). Results. Overall, the 8-year actuarial rate of biochemical disease-free survival was 40% in all patients. The 8-year biochemical disease-free survival rate was 45% (standard error [SE] 8%) and 30% (SE 7%) for the adjuvant and salvage group, respectively, from RT completion. When measured from the date of RP, the 5 and 8-year biochemical disease-free survival rate for salvage radiotherapy was 58% and 37%, respectively. The corresponding results for adjuvant RT were similar at 53% and 45%. On multivariate analysis, the Gleason score was the only prognostic factor predictive of prostate-specific antigen failure in the salvage group. No prognostic factor was significant in the adjuvant group. The prevalence of major complications after 3D-CRT was low using physician-reported data. Conclusions. Long-term biochemical control can be achieved in both adjuvant and salvage settings. For patients receiving salvage RT, a Gleason score greater than 7 was predictive of prostate-specific antigen failure. Prospective trials are needed to improve further on these results.