In Europe, short-term radiotherapy is increasingly used in the primary management of rectal cancer. In the United States, postoperative chemoradiotherapy is the standard treatment of choice. The rationale and indications for radiotherapy and possible combinations with chemotherapy are discussed and an overview of all of the randomised trials containing radiotherapy as one randomisation arm is given. Three major indications for radiotherapy can be identified: the reduction of local recurrences in mobile rectal cancer, downstaging of the tumour in primary irresectable tumours and downsizing of low-lying tumours in attempts to more frequently perform a sphincter-saving procedure. For reduction of local recurrences, radiotherapy can be given either pre- or postoperatively, although preoperative therapy is more dose-efficient. Short-term preoperative radiotherapy reduces the number of recurrences and improves survival. Improved survival is also reported after postoperative radiotherapy in combination with chemotherapy, however, the relevance of the radiotherapy component is discussed. Although the debate about radiotherapy is still ongoing, we strongly believe that the results demonstrate that short-term preoperative radiotherapy is the treatment of choice for resectable rectal cancer.