In this study, the effects of intraperitoneal applications N-acetyl cysteine (NAC) an glutathione (GSH) precursor, on GSH and related enzymes, lipid peroxidation activities in the erythrocyte and liver tissue were investigated. For this purpose, effects of the NAS were investigated on playing an important role in detoxification reactions of biomolecules; GSH/GSSG, GSH reductase, GSH-px, NADP/NADPH activity, superoxide dismutase (SOD) and as an indicator of lipid peroxidation malondialdehyde (MDA) in liver toxicity formed by carbon tetrachloride (CCl4). In this study in order to create liver toxicity in rats, CCl4 was applied 3 times with an interval of one day 1 ml/kg intraperitoneal (ip) in 1/1 ratio of olive oil in the form of solution. In order to determine the protective effect of the NAS, NAS application was started 3 days before (ip 50 mg /kg/day) that CCl4 injected to tested group and continued during the experiment. 24 hours after the last injection of CCl4, blood and liver samples were taken under ether anesthesia. It was determined that AST, ALT, GSSG, NADP/NADPH and MDA levels increased importantly in CCl4 group than control group and also observed that the levels decreased with addition of NAS. Also it was observed that GSH, GSH reductase, GSH-Px and SOD levels significantly decreased in CCl4 group than control group, the levels were increased with addition of the NAS. It is concluded that NAS may be useful repairing oxidative damage in liver injury induced by CCl4 and protecting the harmful effects of reactive oxygen species with removing oxygen radicals also may support the defense of tissues against oxidative stress and direct antioxidant effect.