An 80-year-old man with a local recurrence of gastric cancer was treated with S-1 monotherapy leading to a complete response(CR).The patient was diagnosed with gastric cancer and underwent a distal gastrectomy with lymph node dissection. Pathological findings showed tub2>por1, pT3 (SS), pN2, pStage III A.Five months after surgery, the patient presented with redness of the abdominal skin.Computed tomography (CT) revealed massive tumors in the abdominal cavity with invasion to the abdominal wall. He was administered S-1, 80 mg/body/day for 14 days, followed by a 7-day rest.After 2 courses of treatment, CT showed a dramatic reduction of the tumors. After 6 months, the tumor tissue completely disappeared and he had a CR.Administration of S-1 was continued for 2 years and 6 months.There was no relapse for 3 years after discontinuation.S -1 monotherapy appears to be a feasible and effective therapy for elderly patients with recurrent gastric cancer.