The experimental study was carried out to determine the effects of bacteria (B. subtilis or P. acidilactici) alone or combined supplementation in broiler diets on productive performance, bacteria enumeration and some physiological responses. A total number of birds (360 Cobb broiler chickens at seven d of age) were distributed into nine treatments (40 chicks each), each treatment contained four replicates of ten birds as follows: - 1- Chicks were fed the control diet (T1). 2- (T1) + 0.5 g Bacillus subtilis /kg diet.  3- (T1) + 1 g Bacillus subtilis /kg diet.  4- (T1) + 0.5 g Pediococcus acidilactici /kg diet.  5- (T1) + 1 g Pediococcus acidilactici /kg diet. 6- (T1) + 0.5 g Bacillus subtilis+0.5 g Pediococcus acidilactici /kg diet.  7- (T1) + 0.5 g Bacillus subtilis+1 g Pediococcus acidilactici /kg diet.  8- (T1) + 1 g Bacillus subtilis+0.5 g Pediococcus acidilactici /kg diet.  9- (T1) + 1 g Bacillus subtilis+1 g Pediococcus acidilactici /kg diet.  The obtained results of the experiment showed that chicks fed combined supplementation of B.subtilis 1g+ P. acidilactici 0.5g had significantly higher Live body weight, body weight, growth rate, performance index, Immune organs (bursa and thymus) and improved feed conversion ratio, blood parameters, and microbial load. Generally, it could be concluded that the combination of B.subtilis 1g+ P. acidilactici 0.5g can be used in broiler diets as a growth promoter because this combination improved growth performance, gut health and intestinal microbial balance of broilers.