The present study was conducted using sub-therapeutic levels of the antibiotic zinc bacitracin (ZnB) to investigate its effect on the performance and physiological parameters in broilers chicks under dry summer conditions. One hundred and forty day-old broiler chicks (Ross 208) with an average initial body weight of 33.6 ± 1 g were used in the present study. The chicks were divided into five treatment groups (28 bird each) with each group treated with 0, 25, 50, 75 and 100 mg zinc bacitracin/kg basal diet for seven weeks. Each group was further divided into 4 replicates (7 birds each). The increasing graded levels of ZnB resulted in a progressive significant increase in average final body weight (P < 0.01), average total weight gain (P < 0.01), average total feed conversion ratio (P < 0.05), during dry summer compared to the control. Differences in rectal temperature values among birds receiving either the control or the ZnB-supplemented diets were not significant throughout the study period. Feeding the chicken with 75 and 100 mg zinc bacitracin/kg feed resulted in the reduction of respiratory rate mean values from week 2 up to week 7 compared to the control values. The study findings suggest that zinc bacitracin (ZnB) at 100 mg/kg feed can be used efficiently in improving broiler performance and some physiological parameters.