A comparative analysis of the immunological parameters in chickens of industrial crosses, which were fed diets with antibiotics (group 1) and antibiotics in combination with a phytobiotic (group 2), is presented. After 30 days of feeding antibiotic hemoglobin concentration in the blood of laying hens remained unchanged – 87.3-93.2 g/l. On the 30th day of the experiment, in group 1 was noted an increase in the number of leukocytes up to 30.13±2.84∙109/l and the proportion of eosinophils by 29.6%. In the same period, a decrease in the absolute number of immunocompetent cells – T-lymphocytes by 36.6% was observed and absorption capacity of phagocytes by an average of 27.9%. From the 30th to the 60th day of the experiment in the blood of the chickens of group 1, the dynamics of the increase in the CIC level was recorded (up to 143.8±12.1 c.u.). When antibiotic was introduced into the diet of laying hens in combination with a phytobiotic in group 2, only by the 60th day, the number of erythrocytes was increased by 17.4% compared to the “background values” (82.1±5.2∙1012/l). Hemoglobin fluctuation amplitude did not exceed 7%. On the 30th day of the experiment in laying hens of group 2, a decrease in the number of immunocompetent cells by 20.8% was registered compared to the background values. On the 45th day of the experiment after the abolition of antibiotic and phytobiotic, the content of T-lymphocytes did not significantly differ from the background values.