The aim of this work was to investigate the effect of Ochratoxin A (OTA) and Silymarin on serum lysozyme concentrations, complement and betalysin activity in broiler chickens. In this experiment 144 one-day-old Ross 308 male broiler chicks were used. All chicks were divided in four groups of 36 birds each: Group 1: Basal diet (BD) with no supplementation of Ochratoxin A (OTA) and Silymarin; Group 2: BD with 1.0% Silymarin; Group 3: BD with 3.0 mg/kg OTA; Group 4: BD with 3.0 mg/kg OTA plus 1.0% Silymarin. It was found that lysozyme concentration in the 2nd group there is a significant difference to groups 3 and 4. The immunosuppressive effect of Ochratoxin A is underlined but no protective effect of Silymarin in the group 4 was found. The alternative pathway of complement activation (APCA) is affected in the group 4. Betalysine there is a significant decreasing in the group 3 but slightly increasing of Betalysine in 4th group. Based on these results it can be concluded that OTA there is an immunosuppressive effect on the studied traits and there is a positive effect of Silymarin only on serum betalysine.