The protective effect of Yangguksanwha-tang (YST) against hypoxia-reperfusion insult was investigated in PC12 cells. To elucidate the mechanism of the protective effect of YST, cell viability, the changes in activities of superoxide dismutase, glutathione peroxidase, catalase, caspase 3 and the production of malondialdehyde were observed after treating PC12 cells with YST which was metabolized by rat liver homogenate. Pretreatment of YST with liver homogenate appeared to increase its protective effect against hypoxia-reperfusion insult. The result showed that YST had the highest protective effect against hypoxia/reperfusion at the dose of $2;{mu}g/ml$ in PC12 cells, probably by recovering the redox enzyme activities and MDA to control level.