To reveal the influence of intercalating fragment on the affinity to DNA aminoacetylhydrazones of 9-formylacridine and 9-formylanthracene are synthesized and their properties as intercalators and ability to inhibit the polymerase chain reaction are studied. It is shown, that the acridine derivatives (lg K а = 7.37 - 8.04) are more affine to DNA than the anthracene derivatives (lg K а = 5.37 - 6.12). Both acridines and anthracenes are characterized by insignificant ability to inhibit PCR. Correlation between affinity to DNA and ability to inhibit replication is absent.