Small bowel cancer is frequently detected at an advanced stage and its prognosis is poor. We report on a patient with small bowel cancer with positive peritoneal cytology who survived for 5 years without recurrence after surgery.The case involved a 73-year-old woman who had undergone partial resection of the small intestine and lymphadenectomy for a small bowel tumor with obstruction. Pathological examination confirmed papillary adenocarcinoma with partial serosal invasion. Ascites cytology indicated a class V tumor. Adjuvant chemotherapy with TS-1 was administered for 20 months, and the patient has survived without evidence of disease for over 5 years.In this case, it is possible that TS-1 chemotherapy was effective for prevention against small bowel cancer recurrence.Furthermore , peritoneal cytology in patients with small bowel cancer should be evaluated as a predictor of prognosis.