In order to understand the impact of viral hepatitis on anti-oxidant defence system of the body, blood levels of superoxide dismutase (SOD), an enzymatic anti-oxidant, and total anti-oxidant (TAO) were evaluated and co-related to etiological viral hepatitis in various forms of liver diseases. A total number of 110 patients including 50 patients with acute viral hepatitis (AVH), 30 patients with chronic active hepatitis (CAH) and 30 patients with cirrhosis of liver were analysed for different hepatitis viral markers and the anti-oxidant levels in their blood. For comparison, blood from 100 healthy persons were also simultaneously tested for anti-oxidant levels. Analysis of results indicated that none of the patients belonging to these three liver diseases had hepatitis A viral (HAV) and hepatitis D viral (HDV) infections. AVH group had mainly hepatitis B viral (HBV), hepatitis C viral (HCV) and hepatitis E viral (HEV) infections, CAH group had B and C infections and cirrhosis group had B, C and E infections. A sizeable number of patients in each group had no markers and were labelled as non-BCE group. On co-relating anti-oxidant levels to viral etiology in these patients, it was observed that in comparison to healthy control group, SOD level was significantly reduced in all the patients irrespective of the viral etiology (P<0.05-0.001). The impact of different viruses on reduction in SOD level was recorded to be the same with no significant difference in SOD level between any two viral infections. On the contrary, TAO level in the majority of patients was found to be comparable with that observed in healthy persons. An appreciable change in SOD level but little impact on TAO level during viral hepatitis may be explained by the possible adaptive rise of some other anti-oxidant level in the blood of these patients.