The two-drug combined chemotherapy of platinum and fluorouracil has been reported to efficiently kill tumor cells as the first-line treatment for advanced gastric cancer.However,the effect of these drugs on T cells remains unclear.Here,we showed that T cells including CD4+ T cells and CD8+T cells of the patients with advanced gastric cancer after platinum and fluorouracil chemotherapy exhibited enhanced ex vivo proliferation ability as compared to that before chemotherapy.In addi-tion,platinum and fluorouracil also promoted the differentiation of human T cells into Th1 and Th9 subtypes and cytotoxic T lymphocytes (CTLs) in vitro and in vivo.Accordingly,the combina-tion therapy greatly suppressed tumor growth with increased tumor infiltration of Th1,Th9,and CTL cells in a mouse tumor model.Moreover,in activated T cells,long-term treatment with these two drugs further facilitates T cell activation along with promoted nuclear factor-κB (NF-κB) acti-vation.Our findings demonstrate a previously unidentified function of platinum and fluorouracil combination chemotherapy in promoting T cell-mediated antitumor immunity.