Helicobacter pylori, a gastric pathogen, binds to various blood group antigens, including the Lewis types, present in the gastric tissue and a relation between the presentation of the ligands and the overall strength of binding has been assumed. Synthetic Lewis b tetra- and hexasaccharide conjugates are available but not the analogous pentasaccharide. An efficient synthesis of the amino spacer equipped Lewis b pentasaccharide, 3-aminopropyl alpha-L-fucopyranosyl-(1 -> 2)-beta-D-galactopyranosyl-(1 3)-[alpha-L-fucopyranosyl-(1 -> 4)]-2-acetamido-2-deoxy-beta-D-glucopyranosyl-(1 -> 3)-beta-D-galactopyranoside, is presented to enable further investigation of the carbohydrate recognition process of H. pylori. (C) 2010 Elsevier Ltd. All rights reserved.