This work was devoted to the influence of probiotics "Vetom 4" and "Zoonorm" in broiler chickens ration on the formation of intestinal microbiocenosis: on its quantitative and qualitative composition as well as on the feed digestibility and body weight dynamics of chickens. The studies show that probiotic preparations optimize the composition of the intestinal microbiota, increasing the content of representatives of normoflora: bifidobacteria and lactobacilli and reducing the content of pathogenic and conditionally pathogenic microflora: staphylococci, enterococci and BSCP. For example, the use of probiotic "Vetom 4" increased the amount of bifidobacteria by 1.09 Lg CFU/g, lactobacilli - by 0.98 Lg CFU/g, reduced the percentage of staphylococci, enterocococci and BSCP relative to all groups of determined bacteria. At the same time, because of the balance experiment, there was an increase in the digestibility of feed nutrients relative to the control group counterparts. Digestibility of organic matter increased by 2,38 %, crude protein by 2,45%, crude fat by 1,37%, percentage of nitrogen taken with feed by 2,5%, percentage of calcium by 3,53%. When probiotic "Zoonorm" was added to the diet, the content of lactobacilli increased by 1,77 Lg CFU/g, bifidobacteria - by 1,36 Lg CFU/g, while the percentage of staphylococci, enterocococci and BSCP decreased. Digestibility coefficients were also increased: organic matter by 3.6%, crude protein by 2.38%, crude fat by 1.06%, percentage utilization of nitrogen taken with feed by 2.25%, percentage utilization of calcium by 3.26%. In addition, by weighing the broiler chickens individually, we found higher dynamics of growth of body weight of chickens, which at the end of the experiment was 301 g more than the control values by adding probiotic "Vetom 4" to the diet and 230 g more when "Zoonorm" probiotic was added to the diet.