In December 1994, The French Consensus Conference on the Treatment of Rectal Cancer stated that: "Preoperative irradiation improves local control in T3 and T4 resectable rectal cancer patients and is recommended". Recent data indicate that this approach not only reduces local failure but also increases overall survival. The therapeutic ratio depends on the total dose delivered and technical parameters. Inadequate radiotherapy techniques leeds to increased toxicity and masks the potential benefits of the treatment. Combined preoperative chemo-radiotherapy, a promising issue in rectal cancer patients, is now under evaluation in a large European phase III trial (EORTC 22921).