The synthesis of the O-peracetylated trisaccharide azide with 4-O-(α-L-fucopyranosyl)lactosamine (Lewisa antigen) structure is described. Reduction of the azide and condensation of the resulting trisaccharide amine with N-trichloroethoxycarbonylaspartic acid α-allyl ester (Teoc-Asp-OAll) delivered the desired Lewisa antigen asparagine conjugate.