The aim of this study was to determine the effect of acute intoxication with chlorfenvinphos on the liver reduced glutathione (GSH) level and the activities of two enzymes involved in glutathione metabolism, as well as the activity of catalase (CAT), glucose-6-phosphate dehydrogenase (G6PDH) and the level of liver hydrogen peroxide. The concentration of malondialdehyde (MDA) was determined as lipid peroxidation index. Rats were divided into two groups: the control group, which received oil intragastrically by stomach tube, and the experimental groups, which received oil solution of chlorfenvinphos (CVP) in doses of 0.02 LD₅₀, 0.1 LD₅₀ or 0.5 LD₅₀. After 1, 24, 48 hours of intoxication with chlorfenvinphos, the livers were quickly removed and placed in iced 0.9% NaCl containing 0.16 mg/ml heparin. The liver glutathione peroxidase (GPx) and reductase (GR) activities as well as GSH and hydrogen peroxide levels were determined using Bioxytech Assay kits. CAT activity was determined by Aebi method, G6PDH activity was measured using Sigma Assay kit. MDA level was determined by Buege and Aust method. The changes of examined parameters of antioxidative system as well as lipid peroxidation index were found. The correlation between MDA concentration and the elements of enzymatic and non-enzymatic antioxidative system was determined. A statistically significant correlation was found only between MDA level and G6PDH activity. In conclusion, it is suggested that G6PDH play a key role in the defence against oxidative stress induced by intoxication with chlorfenvinphos.