OBJECTIVE To study the inhibition effects of ziyuglycoside Ⅱ on various tumor cells and the molecular mechanism underlying the ziyuglycoside Ⅱ-induced apoptosis of tumor cells.METHODS SRB method was used to measure the effect of ziyuglycoside Ⅱ on the proliferation of cancer cells in vitro and western blot was used to test influences of ziyuglycoside Ⅱ on three pathways of apoptosis.RESULTS The intracellular ROS level of MDA-MB-231 was significantly up-regulated when treated with ziyuglycoside Ⅱ,which resulted the expression of CHOP and triggered the endoplasmic reticulum stress response.Besides,we observed that the expression of Bcl-2 was downregulated while the expression of Bax was up-regulated,which suggested the activation of mitochondrial apoptosis pathway.We also noticed the up-regulation of DR4 and DR5,which associated with the activation of death receptor pathways.CONCLUSION Through the activation of three apoptosis pathways,ziyuglycoside Ⅱ can inhibit the proliferation and promote the apoptosis of tumor cells.