Abstract: BACKGROUND AND AIM: To study the roles of Bid in vitamin E succinate (VES)_induced apoptosis of human gastric carcinoma SGC_7901 cells. MATERIALS AND METHODS: The activation of Bid was detected by western blot. Bid was blocked by transient RNA interference (RNAi), and apoptotic rate, mitochondrial transmembrane potential (ΔΨm), the amount of cytosolic cytochrome C and the level of PARP cleavage were determined in Bid_negative cells and Bid_positive cells. RESULTS: Bid was activated by VES. Compared with Bid_positive cell, VES caused lower apoptotic rate, higher mitochondrial transmembrane potential, decreased release of cytochrome c to cytosol and lower level of PARP cleavage in Bid_negative cells. CONCLUSION: This study suggested Bid might play an important role in VES_induced apoptosis of human gastric carcinoma SGC_7901 cells.