In this investigation the influence of anabol, a biopolymer preparation incorporated into a complex of extracted components obtained from the surface layer of Lactobacillus bulgaricus cell wall, on some functional activity characteristics of mononuclear phagocytes has been studied. The injection of the preparation in a dose of 20 mg/kg of body weight 24 hours prior to the experiment leads to a decrease in the time necessary for the elimination of one-half of the total amount of ink from the blood stream and to an increase in the content of fibronectin in the blood plasma of rats. The activation of the metabolic activity of resident and induced macrophages, evaluated by the nitro blue tetrazolium reduction test, is observed. On the next day after the injection of anabol the sharp increase of the pool of granulocyte and microphage precursors is observed; the stimulating effect may be retained as long as 3 days. The results thus obtained indicate that anabol acts on different elements of the system of mononuclear phagocytes and can be effective in the complex therapy aimed at the increase of the body resistance to any toxic substances and bacterial infection.