S-1 is a novel oral anticancer drug, composed of tegafur (FT), gimestat (CDHP) and otastat potassium (Oxo), based on the biochemical modulation of 5-fluorouracil (5-FU). S-1 plus irinotecan (CPT-11) for advanced colorectal cancer as expected showed equally good results as these with CPT-11 plus infusional 5-FU/LV (FOLFIRI regimen). A case of unresectable lymph node metastasis from colon cancer successfully treated with S-1 plus CPT-11 is reported here. A 65-year-old man had metastasis to the lymph nodes in the left supra clavicular region and the superior mesenteric artery. S-1 plus CPT-11 was chosen for the treatment. After 2 courses, since grade 2 toxicity for dysgeusia was observed, S-1 administration was shortened. After 3 courses of the revised regimen, the enlarged lymph nodes disappeared on conventional CT and fluorine-18 fluorodeoxyglucose positron emission tomography with CT (FDG-PET/CT) and the case was assessed as a complete response (CR). Because CR was continued by an additional four courses of treatment, the regimen was changed to a single administration of S-1. Although eighteen months have passed since the induction of CR by S-1 plus CPT-11 therapy, no symptoms or findings of relapse have been observed.