We herein report 2 cases of gastric cancer treated by S-1 and oxaliplatin combination therapy before later undergoing gastrectomy. The pathological results of both cases demonstrated complete response. Case 1 had a giant tumor which was suspected to have invaded the pancreas. Case 2 was associated with extensive lymph node metastasis. Based on the findings of these 2 cases, preoperative chemotherapy with S-1 and oxaliplatin for advanced gastric cancer shows sufficient efficacy.