Since the first reports in the late 1950's, a large amount of data have been collected. The analysis of the main evidence from the major randomized trials will be analyzed in this paper according to preoperative, postoperative and chemoradiation approaches. Fifteen randomized preoperative trials were reported; they have been grouped according to the fractionation schedule. In the hypofractionation group (5 Gy for fraction), all five studies that delivered 3-5 doses in one week had a significant improvement in local control and one of them also showed improvement in survival. Operative mortality was higher in the radiotherapy arm if inadequate techniques had been applied. In 3 out of 8 studies with conventional fractionation there was a significant improvement in local control, but no impact in survival was detected. No studies with total dose lower than 34 Gy had an improvement in local control. None of the six randomized postoperative studies showed an improvement in local control or survival. In all trials the local control rate was uniform; ranging from 76% to 84%. Toxicity was higher in the radiotherapy arm. One preoperative and five postoperative randomized studies that used chemoradiation were analyzed. One postoperative chemoradiation study showed a significant improvement in survival in comparison to the surgery arm, and another showed the same advantage compared to the postoperative arm. Protracted infusional administration of 5FU concomitant to radiotherapy showed better survival than bolus administration. No advantages were shown in using MeCCNU or Levamisole in two studies. Toxicity was high and related to the dose and the modality of administration of the drugs in order to adequately treat the different stages of rectal cancer, patients must be carefully selected in order to prescribe the most effective and the least toxic treatment for the individual stage; organ preservation should be an essential goal for its impact on quality of life, and the cost estimates should be taken into account.