The aim of this study is to determine the oxidant and antioxidant parameters in paratuberculosis positive cattle sera. Paratuberculosis is a zoonotic disease in cattle infected with Mycobacterium avium. The analysis did not show any significant difference in serum superoxide dismutase (SOD) and glutathione perioxidase (GSH-Px) activities of paratuberculosis positive group and the control groups. The serum adenosine deaminase (ADA) activity (P<0.05) and malondialdehyde (MDA) levels (P<0.001) were however observed to be elevated in paratuberculosis positive cattle. In conclusion, it was supposed that elevation in serum ADA activity was due to cell mediated immune system stimulation by Mycobacterium avium subsp and the increase in MDA level might be due to the increase in lipid peroxidation because of affected membrane lipids by infection. In spite of that, a nonrelative increase was observed in SOD and GSH-Px activities. This increase suggested that it can be a defense mechanism against increased free radicals together with lipid peroxidation.