AIM To study the ability of polyoxydonium (PO) to influence on adhesive properties of C. diphtheriae. MATERIALS AND METHODS Ability of PO to influence on adhesive properties of toxigenic and nontoxigenic strains of C. diphtheriae isolated from patients, carriers, contact persons as well as from healthy persons during prophylactic examinations of population in Rostov-on-Don and Rostov region was studied. RESULTS It was established that addition of PO in cultivation medium always suppressed adhesive activity of C. diphtheriae. In experiments on breaking of adhesion the blocking effect of PO on adhesive characteristics of bacteria had dose-dependent pattern and was pronounced when PO was used in concentration of 1200 mcg/ml. CONCLUSION Obtained data prove that PO has marked antiadhesive activity against both toxigenic and nontoxigenic strains of C. diphtheriae, which could be used for the treatment of diphtheria infection.