The repeatingunits 2-O-beta-D-glucopyranosyl-L-ribitol 4'- and 1-phosphate of Haemophilusinfluenzaetype a capsularantigen have been synthesised by condensation of an alpha-D-glucopyranosyl bromide derivative with 5-O-allyl-1,2,3-tri-O-benzyl-D-ribitol followed by selective deprotection of HO-4' or HO-1, phosphorylation, and removal of the blocking groups.