Saururus chinensis Baill has been used in Korean folk medicine for the treatment of various diseases such as edema, Jaundice, and furuncle. The components of this plant were extracted into four fraction. Among the four fraction, hexane and ethyl acetate fraction were highly toxic to 3T3 mouse embryo fibroblast and Raw 264.7 mouse macrophage, but n-butanol and residue fraction did not show any toxic effect to those cell lines. n-Butanol and residue fraction exhibited antioxidant effects on hydro-gen peroxide, hydroxyl radical, and superoxide anion directly in vitro and in the 3T3 fibroblasts. All the four fractions inhibited lipid peroxidation measured by thiobarbituric acid reactive substances (TBARS) formation. In addition, n-butanol and residue fraction showed inhibitory effects on lipopolysaccharide (LPS)-induced nitric oxide production, and also down-regulated inducible nitric oxide synthase (iNOS) mRNA transcription 6 h after LPS stimulation in Raw 204.7 cells. Only n-butanol fraction, which mainly consists of flavonoids, inhibited NF-kB activation by decreasing IkBa degradation 90 min after LPS stimulation. horn the results, it is suggested that this plant could be a good candidate material for drug development based on its antioxidant and/or anti-inflammatory constituents.