Adjuvant chemotherapy aims to eradicate residual micro-metastatic tumor cells existing at distant sites outside the surgical field. The current standard adjuvant chemotherapy is S-1 for 1 year or capecitabine plus oxaliplatin for 6 months after D2 gastrectomy. However, there are some rooms in the overall survival of Stage III. Neoadjuvant chemotherapy(NAC)is a promising approach that combines intensive chemotherapy with high compliance; however, it is under development in Japan. Two JCOG phase II trials suggested that NAC was effective for bulky nodal disease. For scirrhous-type malignancy, a JCOG phase III trial is currently ongoing investigating the efficacy of a NAC regimen of S-1 plus CDDP. Another group is conducting 2 randomized phase II trials to compare different regimens and courses of NAC. So far, 2 courses of S-1 plus CDDP or 3 courses of S-1 plus oxaliplatin can be recommended as candidates for the test arm of future phase III studies of NAC.