This research aims at studying the effects of adding green tea and vitamin E on the performance, blood parameters, immune system, visceral traits, and blood cells in broilers under dexamethasone stress. In this experiment, 210 male broiler chicks were studied by completely randomized block design in 7 treatments, and each group with three replications (each replication with 10 male chicks). Treatment groups, include group 1: control (basic diet, without adding green tea and vitamin E, and no dexamethasone injection), group 2( with green tea and dexamethasone injections, without adding vitamin E), group 3(with addition of 300 mg/kg of vitamin E, without dexamethasone injection and consumption of green tea), group 4(a basic diet containing 1.5% green tea, without vitamin E and dexamethasone injections), group 5(a basic diet containing 300 mg/kg of vitamin E and dexamethasone injection without adding green tea), group 6(basic diet with 1.5% green tea with dexamethasone injection, without adding vitamin E.), and group 7(Basic diet taking 1.5% of green tea and 300 mg/kg of vitamin E with dexamethasone injection). Dexamethasone was injected twice in two stages during the 31th and 33th days for the first time and at 37th and 40th days for the second time of breeding. The minimum feed consumption was observed by green tea, and the maximum feed consumption was observed in the control group with the dexamethasone and vitamin E taking group (P<0.05). The maximum weight gain in the initial growth, growth, and final growth stages were in the control group and the minimum weight gain was in a group of 1.5% added green tea and dexamethasone groups (P<0.05). In this study, consumption of green tea reduced the performance through its effect on reducing feed consumption. Therefore, broilers' weight was reduced. Using dexamethasone as a stressful factor harmed the performance of broilers. Adding the green tea to the blood biochemical parameter reduced blood cholesterol and LDL (P<0.05
