Lymph node swelling in the setting of malignancy generally suggests metastasis of the primary tumor. A granulomatous reaction, i.e. sarcoid reaction, occurring within the lymph nodes draining carcinomas is a well-known but uncommon occurrence. The phenomenon is especially rarely seen in colon carcinoma. We herein report a rare case of a 56-year-old Japanese male with adenocarcinoma of the ascending colon associated with sarcoid reaction in the regional lymph nodes. A typical ileocecal resection and lymph node dissection were performed. Histopathological examination revealed moderately differentiated adenocarcinoma of the ascending colon, and the dissected lymph nodes included epithelioid granulomas with multinucleated giant cells. These findings suggest the existence of a sarcoid reaction associated with colon carcinoma; there was no metastasis in the dissected lymph nodes. The significance of this rare condition is discussed.