This study was conducted in order to investigate the dietary inclusion effects of a commercially available probiotic mixture and an antibiotic on the growth performance, cecal microbiota and small intestinal morphology in broiler chickens. A total of 100 broiler chickens (Cobb 500) were subjected to 35-days of study period. The broiler chickens were randomly divided into four groups named T 1 (control group), T 2 (antibiotic fed group, amoxicillin 200 gm/ton of feed), T 3 (probiotic fed group, Pro.B  250 g/ton of feed) and T 4 (probiotic fed group, Pro.B  500 g/ton of feed), respectively. Body weight gain and carcass yield were measured by electrical balance at seven-days-interval. The role of the used probiotic and antibiotic on intestinal microflora were evaluated by the total E. coli count (TEC), total Salmonella count (TSC), total Lactobacillus count (TLC) and total Bacillus count (TBC) whereas the intestinal morphology was determined by histological examination. The results of this study revealed that the obtained live weight gains were significantly (p<0.01) higher in both probiotic fed groups during the periods of 3 rd , 4 th and 5 th week of age as compared to the control and antibiotic fed groups. Data analysis from the cecum samples showed that the TEC was significantly higher (p>0.01) in the control group as compared to both probiotic fed groups. On the other hand, the TLC and TBC were significantly higher (p>0.01) in both probiotic fed groups as compared to the control and antibiotic fed groups. Both probiotic fed groups showed strong evidence in increasing the length of jejunal villi compared to the control and antibiotic fed groups. Among the probiotic fed groups, T 4 group showed a better response in every evaluated parameter included in this study. The results of this study thus revealed that the probiotic supplementation used on the T4 group promoted the most significant and beneficial influence on the growth performance, carcass yield, bacterial antagonism and intestinal morphology.