The experiment was carried out to investigate the effect of synbiotic on growth performance, hematological (TEC, Hb, PCV, ESR) and biochemical (Cholesterol, Uric acid) parameters in broilers during high environmental temperature. A total of 30, at 7 days old (Cobb-500) broilers were randomly divided into 3 groups (n=6). Heat stress broilers were held at 35 ± 2°C temperature and 70±5% relative humidity respectively where as normal temperature was 25 ± 2°C and relative humidity was 60 ± 5%. Normal control group (NE-T) fed the normal diet with normal environmental temperature. Heat stress groups consisted of HS-A as heat stress control group fed the normal diet; HS-B as synbiotics group fed 0.1g prebiotic and 0.1g probiotic with normal diet. The results revealed that supplementation of synbiotic produced a significantly (p<0.01) increased of the live body weight as compared to normal and heat stress control group. The highest weight gain was recorded in HS-B as synbiotic group (1710.00a ± 3.54 gm) and the lowest weight gain was recorded in HS-A as heat stress group (1303.00e ± 4.899 gm). The hematological parameters (TEC, Hb, PCV, ESR) also significantly (p<0.01) differ compared to the both control. The biochemical parameters in uric acid was a significant (p<0.05) difference among groups and there was no significant (p>0.05) difference among the groups in serum cholesterol after treating with synbiotic. Therefore, it is concluded that synbiotic is essential for the maintainance of broilers performance under heat stress condition.