Experimental studying of efficiency of using new native preparation "Superlymph" ("Immunohelp" Immunology Department, RSMI, Moscow) in therapy of acute pyelonephritis was fulfilled. The preparation constitutes a complex of natural cytokines and antibacterial peptides; it possesses immunomodulating, antibacterial and antiviral effect. In experimental investigations, rationality of using Superlymph in treatment of pyelonephritis was established. The preparation applied in complex therapy of pyelonephritis contributes to decrease in bacteriemia rate among experimental animals infected with uropathogenic strains. It reduces expression of morphological pyelonephritis signs; the preparation does not cause changes in animal peripheral blood indices while using of cephalosporin (cephasoline) group antibiotics induces eosinophilia resulting from allergic effect typical for antibiotics.