THE  ANTIOXIDANT activity of hexane, ethanol or water extracts of chufa tubers (Cyperusesculentus L.) were investigated in vitro using liposome peroxidation systems. Incorporation of 1 mg/ml of chufa oil, water or ethanol extracts of the tubers to phosphatidylcholine (PtdCho) liposomes displayed different antioxidative activity. All fractions possessed antiperoxidation activity in ferrous ions dependent peroxidation stress and in free radical mediated peroxidation by the water soluble initiator 2,2'-azobis (2-aminopropane) dihydrochloride (AAPH), while the water extract possessed the strongest effect. However, in the lipid soluble free radicals initiator 2,2'-azobis (2,4-dimethylvaleronitrile) (AMVN) mediated peroxidation, the antioxidant activity was found only by the oil fraction. The antioxidant activity of chufa oil may be attributed to its fatty acid profile and vitamin E content. Chufa oil contains about 72% of monounsaturated fatty acids, mainly oleic acid and 18.6 mg/100g of vitamin E. The resistance of chufa water and ethanol extracts may be attributed in part to its isoflavones content (20.9µg/g).