Aim: Liver and kidney are exposed to a lot of oxidant substances that are both from exogen and endogen sources. The aim of this study was to investigate the antioxidant effects of C vitamine, Melatonine (MLT) and N-acetylcystein (NAC) in carbon tetrachlorur (CCl4) induced oxidative stress in mouse. Methods: The study involved 6 groups; control group (Group 1), CCl4 group (Group 2), CCl4 + C vitamine group (Group 3), CCl4 + MLT group (Group 4), CCl4 + NAC group (Group 5) and combined (CCl4 + C vitamine + MLT + NAC) group (Group 6) with each group containing 10 mice. Starting from the 4th day of the study 0,4 ml/kg CCl4 were given intraperitoneally (i.p.) to all groups except the control group. In Groups 3, 4, 5 and 6; 150 mg/kg/day C vitamine, 10 mg/kg/day MLT, 150 mg/kg/day NAC and C vitamine + MLT + NAC combination, respectively, were given for 7 days. The malondialdehyde (MDA) level and superoxide dismutase (SOD), glutatyon peroxidase (GSH-Px), catalase (CAT) and myeloperoxidase (MPO) activities were measured in the tissues of liver and kidney of the mice. Results: The MDA and MPO levels in the tissues of liver and kidney of the toxicity group (Group 2) were significantly higher than those of the control group (p<0.01), but the GSH-Px and CAT activities were significantly lower than those of the control group (p<0.01). Compared with the toxicity group; in groups 3, 5 and 6 liver MDA and MPO levels showed a significant decrease (p<0.05) while GSH-Px and SOD activities in group 4 and GSH-Px activity in group 5 showed a significant increase (p<0.05). In kidney, MDA levels in groups 3 and 5 and MPO levels in groups 4 and 6 showed a significant decrease (p<0.05). SOD in group 3; GSH-Px and CAT in group 4; GSH-Px, SOD and CAT in group 5 and SOD activities in group 6 showed a significant increase. Conclusion: The results showed that C vitamine therapy and the combined therapy were effective in preventing oxidative stress in both liver and kidney while MLT increased antioxidant enzyme activities more effectively. Furthermore, NAC was more effective in preventing oxidative stress and increasing antioxidant enzyme activities.