The patient was a 38-year-old woman who visited our hospital complaining of nausea and abdominal pain. A colonoscopy revealed an advanced cancer in the sigmoid colon. A computed tomography (CT) scan showed left hydronephrosis and lymph node metastasis to the left iliopsoas muscle and left ureter. No distant metastasis was found. Since the surgical margins were likely to be positive with a one-stage resection, 3 cycles of FOLFOX4 (folinic acid, fluorouracil, and oxaliplatin)were administered after creating a transverse loop colostomy. Although the tumor decreased in size, the surgical margins were still suspected to be positive. For further regional tumor control, radiotherapy (1.8 Gy/day for 25 days) to the medial region of the left iliac bone and oral UFT/LV (uracil and tegafur/Leucovorin)were administered. A partial response(PR)was determined in accordance with the Response Evaluation Criteria in Solid Tumors(RECIST). Sigmoidectomy with partial resection of the left ureter was performed by laparotomy. The histologic response was assessed as Grade 2 and all surgical margins were negative. Preoperative chemoradiotherapy may be an effective therapeutic option for locally advanced colon cancer resistant to conventional preoperative chemotherapy.