The study was designed to observe antioxidant activities of conjugated linoleic acid (CLA) by determining antioxidant enzyme protein levels [cytochrome P4502 El (CYP2E1), Copper, Zinc-superoxide dismutase (CuZn-SOD), glutathione peroxidase (CSH-Px), glutathione S-transferase (GST)] by Western blot analysis and the levels of ${alpha}$-tocopherol and 2-thiobarbituric acid reactive substances (TBARS) in the liver of chronically ethanol-treated rats. Sixty Sprague Dawley male rats were divided into 3 groups (Control, EtOH, EtOH+CLA). All rats were fed Lieber-DeCarli liquid diet for 4 weeks by pair-feeding against the EtOH group. The liquid diet was supplemented with 1.77g CLA mixture per kg diet in the EtOH+CLA group. Isocaloric maltose dextrin was added in replace of 50g ethanol (36%kcal) for the Control group. Ethanol ingestion significantly increased the levels of CYP2E1 protein and TBARS, but significantly reduced CuZn-SOD protein level and increased GST protein level. There was no significant effect on the level of GSH-Px protein and ${alpha}$-tocopherol in the liver by ethanol. CLA supplementation with ethanol significantly increased the levels of CuZn-SOD, GSH-Px and GST and also significantly attenuated TBARS level, whereas there was no significant effect on the levels of CYP2E1 protein and ${alpha}$-tocopherol by CLA. Overall, the CLA supplemented to ethanol could significantly increase the levels of CuZn-SOD, GSH-Px and GST proteins and reduce the level of TBARS in the liver of chronically ethanol-treated rats.