Most patients presenting with rectal cancer will have "operable" disease. The main aim in treating these patients is to achieve complete surgical resection while minimising the rate of local recurrence. The use of radiotherapy has been shown to decrease local recurrence rates and the evidence suggests that this should be used preoperatively. Here we summarise the important trials both before and after the introduction of mesorectal excision. We highlight some of the important issues, including treatment-related toxicity and patient selection for preoperative treatment.