Objectives : Uncontrolled activation of microglia may directly toxic to neurons by releasing various substances such as inflammatory cytokines, nitric oxide(NO), prostaglandin E2 and superoxide. In this study, the effects of the several subfractions isolated from Coptidis Rhizoma extract were investigated on NO production in LPS-stimulated BV2 microglial cells, Methods : Coptidis Rhizoma extract prepared with 80% methanol, and then fractionated with ethylacetate, chloroform, n-butanol and water. BV2 cells were pretreated four subfractions of Coptidis Rhizoma with various concentrations, and then stimulated with LPS. Cytotoxicity of each fraction was measured by MTT assay. NO production was determined in culture surpernatants by Griess reagent. Results : Ethylacetate, chloroform and butanol fractions of Coptidis Rhizoma extract significantly decreased LPS-induced NO production in BV2 cells as a dose-dependent manner without cytotoxicity. Ethylacetate fraction of Coptidis Rhizoma extract was most effective on inhibition of NO production in LPS-stimulated BV2 cells compared with other fractions. Conclusion : This data indicates that Ethylacetate fraction of Coptidis Rhizoma extract shows strong antiinflammatory effects through inhibition of LPS-induced microglial activation.