Although the value of postoperative radiotherapy has been demonstrated for subsets of patients with rectal carcinoma, the efficacy of postoperative radiation therapy for colonic carcinoma (above the peritoneal reflection) is much less clear. Recent studies examining the failure patterns of colonic carcinoma following resection indicate that local failure increases as a function of bowel mobility, disease extension through bowel wall, and lymph node involvement. Retrospective series reporting the results of postoperative irradiation suggest that postoperative radiation therapy to the tumor bed may be beneficial for patients with Stage B3, C2 and C3 disease with limited nodal involvement. Randomized prospective trials are required to further evaluate the efficacy of such adjuvant radiotherapy.