A factorial experiment (3×3) was conducted to evaluate the response of broiler to stocking density (8, 12 and 16 bird/m2) with probiotic supplementation (Almiral plus® at 0, 1.5 and 2.5 g/l water). A total of 324 one day old unsexed Hubbard broiler chicks were used. All birds were randomly housed in twenty seven floor pens and reared under similar managerial conditions. The most important results obtained could be summarized as follows: Decreasing stocking density to 8 birds/m2 showed the best values of live body weight, live body weight gain, feed conversion ratio, performance index, plasma globulin concentration, net revenue and economic efficiency. However, no significant differences in feed intake, protein efficiency, plasma total protein and albumin due to stocking density. Probiotic supplementation at level 2.5g/l water showed the best value of body weight, body weight gain, feed conversion ratio, protein efficiency, performance index and net revenue, economic efficiency. However, probiotic supplementation didn't have any significant effect on feed intake, plasma total protein, albumin and globulin concentration. According to the obtained results, probiotic (Almiral plus®) can be used at level of 2.5 g/l water to improve broilers growth performance and level of 8 birds/m² can protect birds from the reduction in their growth performance.