Objective : This study was designed to asses the effect of Hwangryunhaedoktang and herbs on Mouse neuroblastoma 2a cells damaged by hypoxia-reoxygenation. Method : Mouse neuroblastoma 2a (N2a) cells were measured by MTT assay and LDH assay after 48h hypoxia and 6h reoxygenation. Mouse neuroblastoma 2a (N2a) cells were treated by Hwangryunhaedoktang and herbs. Result : 1. Hwangryunhaedoktang was effective on LDH assay of hypoxia and reoxygenation. 2. All of herbs were generally effective on LDH assay of hypoxia and reoxygenation. In LDH assay of hypoxia, the effects of herbs depended on concentration. In MTT assay of hypoxia, Coptidis Rhizoma and Gardeniae Fructus were effective. In MTT assay of reoxygenation most of herbs were not effective. But Phellodendri Cortex was effective in high concentration. Conclusion : The results imply that Hwangryunhaedoktang and all herbs of it nay have protective effect on dementia and aging.