In the work the data about pathomorphosis of the experimental pseudo-tuberculosis infection under the effect of tinrostim (immune active peptide, activating the system of mononuclear phagocytes) are shown. On the guinea pigs model it is shown, that tinrostim as monotherapy caused reduction of bacterial count, decrease in intensity of circulation changes in inner organs, stimulated macrophages and reparative reaction with cellular detrit resorbtion in the centers of an inflammation. Nonpureblood mice were introduced tinrostim in a combination to gentamycin and it considerably reduced expressiveness of the necrotic component of pathological process and septicopyemia, and also the phenomena of secondary immunodeficiency, promoted the development of immune morphologic reactions in inner organs.