Three hundred commercial white leg horn birds of 67 week old were divided into two groups. Group I was fed ZnO (3g/Kg) for three (3) weeks while the other group II was fed normal diet. In Zn treated birds body weight, pituitary, brain, spleen, liver and heart decreased significantly except kidney. Total oxidant status (TOS) of liver, heart, kidney while TAC, ALT and AST cortisol, thyroxine, homocysteine was significantly high. Likewise total antioxidant capacity (TAC) of heart, kidney and muscle decreased significantly as compared to control birds. Serum concentration increased significantly...