The patient, a 40-year-old woman, underwent total gastrectomy and excision of the pancreatic tail, spleen and gallbladder for gastric cancer in September 2000. The lesion was judged to be P1, SE, H0, N2 and Stage IV and the patient was managed on a regular schedule as an outpatient. In September 2004, she passed blood-stained feces and rectal palpation detected a hard nodule at the anterior rectal wall. A fiber optic examination of the sigmoid colon detected an ulcerous lesion with a hemorrhage at the anterior rectal wall. A biopsy revealed the lesion to be Group V poorly differentiated adenocarcinoma. Starting in October 2004, 100 mg/day of TS-1 was administered for 3 weeks; intravenous drip infusion of 100 mg/body of CDDP was conducted in the second week for a period of 24 hours. After 3 courses of this regimen, a fiber optic examination of the colon conducted in February 2005 no longer detected the rectal tumor, leaving only a cicatrix. Upon a CT examination, the para-aortic lymph nodes that had been enlarged were notably reduced in size and an improvement was eminent in the hypertrophic rectal wall. The patient no longer experienced constipation or melena. Her clinical course is being observed while an oral administration of 100 mg/day of TS-1 continues.