Objectives: Melia toosendan(MT) has been used as a traditional Korean herbal medicine, and today it is used as a medication for colic, side aches, heartache and other disorders of liver. The aim of this study was to determine whether fractionated extracts of MT inhibit free radical generation such as DPPH radical, superoxide radical and nitric oxide, production of nitrite, an index of NO, PGE2, iNOS, COX-2 and proinflammatory cytokines in lipopolysaccharide(LPS)-treated RAW 264.7 macrophages. Methods: MT extract prepared with methanol, and then fractionated with hexane, dichloromethane, ethylacetate, n-butanol and water. Inhibitory effect of MT onto free radical generation was determined by measuring DPPH, superoxide anions and nitric oxide scavenging activities in vitro. Cytotoxic activity of extracts on RAW 264.7 cells was measured using 5-(3-caroboxymeth-oxyphenyl)-2H-tetra-zolium inner salt(MTS) assay. Intracelluar oxidation was analysed by DCF-DA assay. The nitric oxide(NO) production was measured by Griess reagent system. The levels of iNOS and COX-2 expression were confirmed by western blot. And pro inflammatory cytokines were measured by ELISA kit. Results: Our results indicated that fractionated extracts, especially dichloromethane and ethyl acetate extracts, significantly inhibited free radical generation, the LPS-induced $H_2O_2$, NO, $PGE_2$ production and iNOS, COX-2 expression accompanied by an attenuation of TNF-${alpha}$, IL-1${eta}$ and IL-6 formation in macrophages. Conclusions: These results indicate that dichloromethane and ethyl acetate extracts of MT have potential as an agent of chronic inflammatory diseases.