Radiotherapy is a well-accepted treatment modality for patients with localised prostate cancer. Provided that radiotherapy is applied with a sufficient radiation dose, it is as effective as radical prostatectomy. Different radiation modalities are available (interstitial brachytherapy, external beam radiotherapy or a combination of both). Various new developments will further increase the value of radiation-based approaches. In this regard, a wider use of intensity-modulated radiotherapy (IMRT) and image-guided radiotherapy (IGRT) will result in higher treatment doses with even lower toxicity rates. Combinations of radiotherapy and hormonal ablation improve local control rates in defined groups of patients. After prostatectomy with positive surgical margins, adjuvant radiotherapy improves disease-free survival rates; in cases of local relapse, salvage radiotherapy is the only potentially curative treatment approach.