Both S1 and XELOX (capecitabine+oxaliplatin) have been recommended as an adjuvant treatment for gastric cancer according to the guidelines of the National Comprehensive Cancer Network (NCCN). This study compared the two regimens in terms of monetary costs, assuming equal efficacy of both regimens. Chemotherapy cost data of 188 patients were collected from the medical records, 91 for the S1 group and 97 for XELOX. Costs were classified as direct costs (chemotherapy, hospitalization, venous access, and tests), adverse event-related treatments costs, and societal (travel and time) costs. The total direct costs of S1 and XELOX per cycle per patient were $1938±236 and $2317±315, respectively. S1 cost $27 and $9 less than XELOX on total adverse event-related costs and societal costs, respectively. The total costs of S1 and XELOX were $1994±322 versus $2410±391 per cycle per patient, respectively. The total cost of S1 was 17.3% less than that of XELOX for the average patient. All the differences were statistically significant. S1, compared with XELOX, could be a more affordable option as an adjuvant treatment for gastric cancer when all healthcare resources are taken into account in China.