Incubation in the presence of structurally modified disaccharides altered the in vitro attachment of Yersinia pestis GB to three human respiratory epithelial cell lines. Each disaccharide resulted in decreased attachment to the alveolar epithelial (A549) cell line. The best inhibitor of attachment for each cell line was the benzylated derivative of Galbeta1-4GalNAc. Highly negatively charged saccharides were efficient inhibitors, particularly for the bronchial epithelial (BEAS2-B) cell line. The data indicate that targeted modification of receptor ligands could offer a novel therapeutic preventing Y. pestis attachment to host cells.