Postoperative adjuvant radiation therapy has achieved special significance based on the results of three randomized studies on stage pT3R1 prostate cancer which provided evidence for prolonged survival in comparison to the "wait and see" strategy. When PSA levels persist or increase after radical prostatectomy, irradiation represents an alternative. In this instance, salvage radiotherapy should be initiated as early as possible, most suitably when the PSA level is <0.5 ng/ml. Side effects of percutaneous radiotherapy using modern techniques are minimal in this stage; severe grade 3 or 4 late sequelae occur in <3% of cases. Low dose rate (LDR) brachytherapy as monotherapy is a primary treatment option for low-risk tumors. In patients with intermediate-risk tumors, data are controversial and cannot be assessed conclusively. LDR brachytherapy should not be administered in high-risk tumors. High dose rate (HDR) brachytherapy combined with percutaneous radiotherapy as an example of a typical dose escalation approach is a primary option for intermediate- and high-risk prostate cancer. Whether additional hormone therapy is needed with HDR brachytherapy is unclear. HDR monotherapy can only be recommended in the clinical trial setting.