Objective To explore the role of Vav3 gene in multidrug resistance (MDR) of gastric cancer and the related mechanism. Methods QRT-PCR was used to examine the expressions of Vav3 gene in gastric cancer tissues, tumor-adjacent tissues, human gastric cancer cell line SGC7901, and gastric epithelial cell line GES-1. Then Vav3-siRNA was synthesized and tansfected into SGC7901 cells. MTT assay was then used to determine the inhibition rates of tumor cells exposed to chemotherapeutic agents (5-FU, L-OHP) before and after Vav3-siRNA transfection. Real-time RT-PCR and Western blotting analysis were used to observe the expressions of inhibitor of apoptosis proteins (IAPs): xIAP, Survivin, and Livin; meanwhile, the expression and activity of Caspase-3 and Caspase-8 were also determined. Results Vav3 was over-expressed in gastric cancer tissues and gastric cell line compared with those in tumor-adjacent tissues and gastric epithelial cell line GES-1(P<0.05). Expression of Vav3 was significantly inhibited by Vav3-siRNA (P<0.01). Inhibition rates of tumor cells exposed to 5-FU and L-OHP were significantly increased 48 h after Vav3-siRNA tansfection (P<0.05). The expressions of xIAP and Survivin were significantly decreased in cancer cells after Vav3-siRNA tansfection (both P<0.05), and no notable change was found for Livin expression; also the expression and activity of Caspase-3 and Caspase-8 protein were significantly increased after Vav3-siRNA tansfection in SGC7901 cells (all P<0.05). Conclusion Vav3 can participate in MDR of gastric cancer by regulating apoptotic pathways, and inhibition of Vav3 can help reverse MDR of gastric cancer cells by regulating some IAPs.