In this study we aimed to determine the antioxidant effects of Cocoa ( Theobroma cacao L.), which is commonly used in both chocolate and cocoa drinks all over the world , on lipid peroxidation, alanine transaminase (ALT), aspartate transaminase (AST), glutathione (GSH) and protein oxidation levels in carbon tetrachloride (CCl4 ) treated for male Wistar rats. Two control groups and one treatment group of rats were formed. The control groups were nourished with a standard diet, while the Cocoa group was nourished with standard diet which was enriched with % 6 by weight dried Cocoa powder. After three months, a single dose of carbon tetrachloride (CCl4 ) was performed in Control II (CCl4 ) and Cocoa groups (1ml/kg, as 20% in olive oil) intraperitoneally and single dose of olive oil was administered (1ml/kg,i.p.) in the same way as rats in Control I group. They were sacrificed two hours later. Lipid peroxide levels in liver, protein oxidation in liver, glutathione levels in liver, ALT and AST in plasma were measured. Cocoa decreased liver lipid peroxide, liver glutathione levels and plasma ALT and AST activities previously increased by CCl4 treatment, to the Control I levels The protein oxidation levels in the rats in the Cocoa group compared with the rats in CCl4 treated control group were found to have significantly lessened. These fi ndings suggest that cocoa has strong antioxidant activity because of the fact that cocoa inhibits liver injury.