A 54-year-old woman visited our hospital with a chief complaint of lower abdominal pain and melena. The patient was diagnosed with sigmoid colon cancer using colonoscopy. Abdominal CT revealed metastases to para-aortic lymph node, so our diagnosis was unresectable sigmoid colon cancer. She underwent a transverse colostomy to avoid stenosis. Two weeks after surgery, she underwent a 1-week chemotherapy regimen (CPT-11 80 mg/m(2)/week+5-FU 2,000 mg/m(2)/week+l-LV 250 mg/m(2)/week) modified AIO regimen combined irinotecan for 3 weeks, followed by a 1-week rest interval as one course. Throughout the period of treatment, there was no adverse event, and this regimen has been maintained for 5 courses. After 5 courses of chemotherapy, primary tumor and metastases to para-aortic lymph nodes were remarkably reduced on colonoscopy and abdominal CT. So, she could undergo curative resection. Pathological efficacy was Grade 3, a complete response. This combination therapy may well be useful for advanced colon cancer patients.