The extract from Smilax china root has been used as medicinal remedy and reported to retain antimicrobial and antimutagenic acitivities. In this study, a possible presence of antioxidant activity of Smilax china root extract was investigated. Methanol extract (Me) revealed the presence of high 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity (IC50 7.4 microg/ml) and protective property of cell's viability. Further fractionation with various solvent extraction and assay showed high levels of DPPH free radical scavenging activity in the ethyl acetate, butanol and water extracted fractions. In addition, V79-4 cells treated with Me of Smilax china root induced an increase of superoxide dismutase, catalase and glutathione peroxidase activities in a dose-dependent manner between 4-100 microg/ml. These results suggest that the medicinal component of the root of Smilax china extracts also contains antioxidant activity.