We report patients with advanced Stage IV gastric cancer responding to chemotherapy with S-1 or UFT. Case 1: The patient was a 59-year-old man with Stage IV gastric cancer because of CY 1. After surgery, chemotherapy with S-1 (100 mg/body/day) was performed for one year and 11 months. At present, 5 years and 5 months after surgery, this patient shows no signs of tumor recurrence. Case 2: The patient was a 68-year-old woman with Stage IV gastric cancer because of P 1. She was treated with 200 mg/day of UFT for one year and 9 months. At present, 5 years after surgery, she shows no signs of tumor recurrence. We considered that the longterm survival of such patients is attributable to chemotherapy with S-1 or UFT. The OPRT activity of the two cases was high, so chemotherapy with S-1 or UFT was thought to be effective for them.