Chungpesagan-tang (CST) has been traditionally used in Korea as a therapeutic for cerebral ischemia. To understand the protective mechanism of CST on hypoxia/reoxygenation insults in N2a cells, the cell viability was determined with the treatment of water solution and several solvent fractions of CST. The highest cell viability occurred when the cells were treated with the hexane soluble fraction of CST. Hypoxia/reoxygenation insults were shown to decrease the glutathione peroxidase (GPx) activity and the level of glutathione (GSH) and increase the superoxide dismutase (SOD) activity. However, treatment with hexane soluble fraction of CST ranging from 0.1 ${mu}g$/ml to 10 ${mu}g$/ml recovered the activities of GPx and SOD and maintained the levels of MDA and GSH at control levels. While hypoxia/reoxygenation insults induced the activation of ERK in N2a cells, treatment with the hexane soluble fraction of CST inhibited the activation of ERK in a concentration dependent manner. In this study, we were able to demonstrate that the bioactive compounds of CST can be effectively transferred into the hexane soluble fraction, and more importantly that CST exhibits protective effects against hypoxia/reoxygenation insults most likely by recovering redox enzyme activities.