Galabiose (Gal alpha 1-4Gal) derivatives were coupled to carrier molecules having mono-, di-, tri-, and tetrameric functionalities, thus creating mono- to tetravalent dendritic galabiosides (1-9). The di- to tetravalent galabiosides were several hundred times more efficient than the monomeric galabiosides in inhibiting hemagglutination by the Gram-positive bacterium Streptococcus suis, resulting in complete inhibition at low nanomolar concentrations. This is unprecedented in the field of inhibition of bacterial adhesion by soluble compounds.