The role of radiotherapy in locally advanced or recurrent colon cancer has not yet been determined. A 59-year-old man undergoing curative resection for advanced descending colon cancer had pelvic lymph node metastasis detected by computed tomography 5 months postoperatively. Intravenous chemotherapy using 5-fluorouracil and CDDP was repeated bimonthly for 7 months; however, his condition deteriorated progressively. External beam radiotherapy (50 Gy) was started thereafter. His serum carcinoembryonic antigen level decreased promptly and abdominal computed tomography showed apparent shrinkage of the metastatic pelvic node with calcification. The patient maintained a partial response for at least 12 months. Radiotherapy has a more crucial role in the treatment of a subgroup of recurrent colorectal tumors.