The current work was conducted to evaluate the effect of feeding Olive leaves and chamomile flowers powders either single or in combination on growth performance, carcass traits, serum parameters and immune response of Sasso broilers. A total number of 126 one-day old unsexed Sasso chicks (average weight 35 g) were obtained from local commercial source and randomly distributed into 6 equal groups each of 21 chicks (7 chicks/replicate). In the first group, birds were fed ad-libitum on starter, grower and finisher basal control diets, while chicks in the second and third groups fed on diets supplemented with 1 & 2% olive leaves powder (OLP). Birds in the fourth and fifth groups fed diets containing 0.75 & 1% chamomile flowers powder, while broilers in the sixth group fed on diet supplemented with 2% olive leaves powder + 1% chamomile flowers powder. Control basal starter, grower and finisher diets were formulated according to guidelines of Sasso breed requirements. Birds were fed according to three phases program (starter, grower and finisher) for 70 days experimental period. Growth performance, carcass traits, serum biochemical and immune parameters were assessed. The results showed that, olive leaves powder supplemented groups (groups 2, 3), chamomile flower powder supplemented group (group 4) and birds in the sixth group (group 6) recorded higher body weight gain (1277.67 ± 33.42g, 1375.75 ± 46.07g, 1277.17 ± 50.30 and 1267.25 ± 37.12 g), respectively and best feed conversion (2.17, 2.03, 2.17 and 2.11) than that recorded by control group (1221.50 ± 47.29g & 2.26). Addition of olive leaves powder, chamomile flower powder or their combination to broiler diets had no significant effect (p < 0.05) on dressing percentage or the relative weights of internal organ compared with the control group. Total serum protein and globulin were significantly increased, while albumin/globulin ratio was significantly decreased in the third group compared with control one. There were significant decreases in serum cholesterol levels in all treatment groups except fourth group, while there was significantly decrease in triglycerides level in sixth group in comparison with other groups and control group. Serum levels of malondialdehyde (MDA) were significantly decreased in the second, third and fourth groups, while there were no significant differences were observed in fifth and sixth groups. Serum catalase enzyme was significantly increased in the third and fourth groups compared with treated groups and control. WBCs counts and lymphocytes % were significantly increased in all treated groups except the third group which show no significant effect. The relative weights of bursa were significantly increased in all treated groups compared with control. There were significantly increased in the relative weight of thymus in third and fifth groups, while the relative weight of spleen significantly increased in fifth and sixth groups comparison with control. Results of the current study concluded that, the best growth performance and immune response were observed in broilers of the third group fed diet containing 2% olive leaves powder.