Relevance. The leaves of the Plantago major are a pharmacopeic medicinal plant raw materials, quite well studied in relation to the chemical compo-sition and spectrum of medical use, but the list of drugs based on them today is limited. In this regard , it seemed to be relevant to study the possibil-ity of developing a drug in the form of a medicinal pencil containing an extraction complex of Plantago major leaves, enriched with flavonoids. To solve this problem, it was necessary to choose an extragent that selectively extracts the biologically active substances of the Plantago major leaves, with a predominance of flavonoids. The aim of the work was a comparative study of the chemical composition and immunotropic effects of the in vitro heteropoly fractions of the leaves of the Plantago major leaves. Material and methods. The object of research was the leaves of the Plantago major. The content of extractive substances in the raw materials was determined by the pharmacopeic method of single extraction using extractants of various polarity: purified water, 40 %, 70 % and 95 % of ethyl alco-hol. The content of the amount of flavonoids in extracts in terms of cinaroside was carried out by differential spectrophotomeria. Heteropoly fractions were obtained by the method of reperculation in a battery from 3 laboratory percolators with subsequent condensation and drying. The assessment of the phagocytic and microbicidal function of neutrophilic granulocytes carried out in vitro on the samples of peripheral blood of conditionally fast-ash persons. Results. It was revealed that the content of extractive substances was reduced with a decrease in the polarity of the extractant, while the content of the extracted amount of flavonoids increased. Comparative immunological studies included the extracts of Plantago major leaves, obtained with the use of 70 % and 95 % of ethyl alcohol. An analysis of their immunotropic effects showed that the fraction extracted by 70% alcohol, statistically sig-nificantly increased the indicators of the phagocytic number, phagocytic index and the relative number of neutrophilic granulocytes that absorb bacte-ria. In addition, in its presence, the digestive ability of neutrophilic granulocytes and the digestion index relative to indicators of the control group in-creased, the activity of NADPH-oxidase and the number of formsan-positive neutrophil granulocytes increased. Conclusions. A comparative assessment of the effect of heteropoly fractions of Plantago major leaves on the phagocytic and microbicidal functions of neutrophilic granulocytes showed that the most pronounced positive immunotropic effect was demonstrated by the fraction extracted with 70% ethanol.