 Patients with advanced gastric cancer have showed poor prognosis. Only 81 of the patients could underwent curative surgery. In those, about 60 of patients would survive after 5 years from the surgery. As a result, role of chemotherapy has been increased. In ACTS-GC trial, S-1 adjuvant therapy after D2 gastrectomy increased overall survival rate in advanced gastric cancer patients. However, subgroup analysis showed that S-1 adjuvant therapy was insufficient in patients with stage III or IV according to the AJCC 6th criteria gastric cancer. In addition, CLASSIC trial demonstrated that oxaliplatin plus capecitabine adjuvant therapy could increase disease-free survival after D2 gastrectomy in advanced gastric cancer patients. Notwithstanding these trial, optimal adjuvant regimen of advanced gastric cancer has not been established. We aimed to evaluate efficacy of S-1 plus oxaliplatin as adjuvant chemotherapy after D2 gastrectomy in stage III according to the AJCC 7th criteria gastric cancer patients. 