Recent advances have been made with the publication of the results of GITSG and NCCTG trials, which demonstrated the significant improvement of survival by combined postoperative radiochemotherapy protocols for Stage II and III rectal cancer. These data show that systemic chemotherapy has a decisive role to play in this policy. Some of the advantages of preoperative irradiation compared with postoperative radiation therapy consist of the improvement of resectability of T4 tumors and the anal preservation for low-lying cancers. These data suggest that preoperative chemoradiotherapy should be applied not only to T4 tumors but also to all T3 tumors even when the transrectal extension is limited. The most usual protocol combines 5-fluorouracil (300-350 mg/m2/day) and leucovorin (20 mg/m2/day) for 5 days, followed by radiation therapy (30-35 Gy in 10 fractions within 12-15 days), with surgery taking place 4 to 8 weeks later, after the tumor has been restaged. Systemic therapy is continued for four more months. T2 cancers should not be excluded from the benefit of preoperative irradiation.