The effects of green tea extract (GTE) on growth performance and immune response were investigated. In a completely randomized design, three hundred sixty Ross 308 strain broiler chicks was assigned to 6 treatments, 4 replicates and 15 chicks in each experimental unit. The experimental treatments were added to the basal (starter, grower and finisher) diets as follows: (1) basal diet,without additives and received only basal diets; (2) basal diets plus 20 IU/kg Vit. E; (3) basal diets plus 3ml/l drinking water GTE with 20 IU/kg Vit. E; (4) basal diets plus 3ml/l drinking GTE; (5) basal diets plus 5ml/l drinking water GTE and (6) basal diets plus 5ml/l drinking water GTE with 20 IU/kg Vit. E. The chicks were fed diet supplied with 3 ml/l GTE (treatment 4) significantly (P<0.05) had higher final body weight, daily weight gain, daily feed intake and better feed conversion ratio. Treatment 6 (5ml/l drinking water GTE with 20 IU/kg Vit. E), non-significantly had higher blood Newcastle antibody titer compared with other treatments. Treatment 5 and 6 had significantly (P<0.05) higher and treatment 4 had a lower Influenza antibody titer, respectively. Non-significantly higher antibody titer against SRBS was observed for treatment 2 (20 IU/kg Vat. E). Adding GTE was not able to improve total antioxidant capacity (TAC) and treatment 2 (20 IU/kg Vit. E) had significantly (P<0.05) higher serum TAC concentration compared with other treatments. The results indicated that the addition of 3 ml/l drinking water GTE had the most positive effects on growth performance traits and application of 5 ml/l GTE alone or in combination with 20 IU/kg diet Vit. E may have a complementary effect on the serum antibody titers against Influenza and had the potential in replacing antibiotics in broiler chicks.