BACKGROUND: The objective of this report was to review the role of adjuvant postoperative radiotherapy (RT) for patients with adenocarcinoma of the colon. METHODS: The authors reviewed the pertinent literature. RESULTS: Data suggested that locoregional postoperative RT improves both local control and survival for patients with T4N0-N1 tumors. There also may be a benefit for patients with T3N1-N2 tumors, but the data were equivocal. Whole abdominal RT may result in a similar benefit but is associated with increased toxicity. CONCLUSIONS: Postoperative RT should be considered for patients with T4N0-N1 colon carcinoma. Locoregional fields should be used. Copyright 2004 American Cancer Society.