A 68-year-old woman presented with severe bowel obstruction and was subsequently diagnosed with stage IV gastric cancer with peritoneal dissemination. She was immediately stabilized in the hospital with the placement of a nasointestinal tube. Abdominal computed tomography showed multiple intraperitoneal nodules consistent with peritoneal dissemination of the gastric cancer. The patient's inability to tolerate oral intake was a contraindication to using S-1 chemotherapy, currently one of the most effective medications used for gastric cancer in Japan. Therefore, she was initially treated with octreotide acetate (OA). Her bowel obstruction was sufficiently attenuated on the seventh day after the initiation of treatment with OA to permit the initiation of oral S-1, along with low-dose cisplatin (CDDP) and radiation. S-1 was orally administered at a dose of 100 mg/day per body (80 mg/m(2) per day) on days 1-28, and CDDP was infused at a dose of 7.8 mg/day per body (6 mg/m(2) per day) on days 1-5, 8-12, and 15-19. Radiation therapy (2 Gy/day for 5 days/week) was performed with the chemotherapy. Despite no change being shown on her imaging findings with the chemotherapy, the patient's bowel obstruction resolved and she was able to tolerate both liquids and solid food orally. She was discharged 2 months after admission. Seven months after beginning the chemotherapy, she was still doing well on outpatient chemotherapy with S-1 and CDDP, and had no decline in her quality of life or progression of her disease.