Background: Current clinical guidelines recommended adjuvant chemotherapy for stage II and stage III gastric cancer after operation. The older patients were underrepresented in clinical trials and the role of adjuvant chemotherapy for older patients is unclear. We aimed to investigate the benefit of adjuvant chemotherapy in older patients with stage II and stage III gastric cancer. Methods: We retrospectively reviewed the medical records of patients with stage II-III gastric adenocarcinoma and underwent curative surgery at Taichung Veterans General Hospital (Taichung, Taiwan) between January 2009 and June 2017. The clinical characteristics and outcomes of patients ≥70-year-old were compared between patients received adjuvant chemotherapy or not received adjuvant chemotherapy. Results: A total of 357 patients were analyzed and 164 patients were older or equal to 70 years old. Majority of the young patients received adjuvant chemotherapy but only two-thirds of the old patients received adjuvant chemotherapy (93.8% vs. 61%; P<0.001). Among older patients, receipt of adjuvant chemotherapy was associated with longer disease-free survival (DFS) (10-year DFS, 45.89% vs. 17.55%; P<0.001) and overall survival (OS) (10-year OS, 61.71% vs. 36.27%; P=0.023) compared with patients who did not receive adjuvant chemotherapy. The total gastrectomy (hazard ratio (HR): 2.26; P=0.015), more advanced stage (HR: 2.71; P=0.018), positive surgical margin (HR: 2.56; P=0.02), elevated baseline carcinoembryonic antigen (HR: 2.37; P=0.026) were independent prognostic factors for OS in patients ≥70-year-old. Notably, the benefit adjuvant chemotherapy in older patients was significant in univariate analysis (HR: 0.53; P=0.025) but was not confirmed in multivariate analysis (HR: 0.52; P=0.072). Conclusions: The benefit of adjuvant chemotherapy in older patients with stage II-III gastric cancer was controversial in this retrospective study. Further prospective studies are needed to investigate this issue.