To evaluate in serum antioxidative deffence parameters--SOD EC.1.15.1.1 (superoxide dismutase), GSH-Px EC.1.15.1.1 (glutathine peroxidase), -SH (sulphhydryl groups) among patients previously diagnosed with borreliosis presently showing antibodies against Borrelia burgdorferi presence. The antioxidative deffence parameters were evaluated in 117 sera of patients with previously diagnosed borreliosis aged x = 43,07. Control group consisted of 39 persons aged x = 40,97 with no detectable anti-Borrelia burgdorferi antibodies in serum. Serologic diagnosis was performed with use of ELISA kit--Borrelia rekombinat IgM, IgG (Biomedica, Austria). Serum activity of antioxidative deffence parameters-- SOD EC.1.15.1.1 (superoxide dismutase), GSH-Px EC.1.15.1.1 (glutathine peroxidase), -SH (sulphhydryl groups) were detected in all patients from both groups. Obtained results were statistically analysed. There was showed no significant difference in serum activity of SOD and GSH-Px in group of former borreliosis patients and control group. Also serum -SH concentration did not differ significantly between both examined groups of patients. No correlation between SOD and GSH-Px serum activity as well as -SH concentration was detected.