We report the case of a patient with advanced gastric cancer producing alpha fetoprotein (AFP), who was treated successfully by adjuvant chemotherapy with S-1 for 36 months. The patient, a 75-year-old man, was admitted for anemia, and was diagnosed as having gastric cancer by endoscopy. Distal gastrectomy was performed in May 2008. Histopathological examination plus immunohistochemistry confirmed that the tumor produced AFP; the tumor stage was determined as T2 N0 P0 CY0, Stage Ⅱ A. The serum AFP level was elevated to 23.4ng/ml. Since the prognosis of AFP-producing gastric carcinoma is poor, the patient was treated with S-1 for three years, guided by the serum AFP level. By the end of three years of chemotherapy, the serum AFP level had returned to the normal range. At present, more than 5 years since the surgery, the patient remains well, without evidence of recurrence (as determined by the serum AFP level and abdominal CT).