Objective: Chronic exposure to carbon tetrachloride induces oxidative stress and liver injuries. Chitosan is a natural substance obtained from the exoskeleton of the crustaceous. The aim of the study was to investigate chitosan's antioxidant properties in rats exposed to carbon tetrachloride. Methods: Forty female Wistar rats (220±15 gr.), randomly assigned to four equal groups, have been used. The control group (10 rats) received 0.9 ml/kg twice a week for 30 days. Thirty rats received 1.2 ml/kg CCl4 25% (diluted in sunflower oil) by gavage twice a week. Ten of them also received 5 mg/kg vitamin E i.m., while ten 3 mg/kg chitosan i.p., daily. Half of them have been sacrificed after 15 days and the rest after 30 days; blood and liver samples have been taken in order to asses liver function (AST) and oxidants/antioxidants equilibrium (malondialdehyde and reduced glutathione from both serum and liver tissue). Results: Chronic exposure to CCl4 increased lipid peroxidation (p=0.01) and depleted the reduced glutathione (p=0.001) both in liver and in the blood serum, and increased the level of the liver enzymes (p=0.0001) as compared to the control group. Vitamin E reduced lipid peroxidation and decrease AST level, but without restoring them to the normal values. Chitosan reduced lipid peroxidation and AST level to values similar to those of the control group. Also, chitosan protected the endogenous glutathione. Conclusion: Vitamin E has moderate antioxidant properties in experimental chronic toxic hepatitis. Chitosan has superior antioxidant and hepatoprotective effects against the injuries induced by chronic exposure to carbon tetrachloride.