A simple and efficient method for the syntheses of clustering-sugar homopolymers from omega-(acrylamido)alkyl glycosides of N-acetyl-beta-D-glucosamine (GlcpNAc) is described. Radical polymerization of the new glycosides proceeded smoothly in an aqueous solution in the presence of ammonium persulfate and N,N,N’,N’-tetramethylethylenediamine and gave water-soluble homopolymers having high density sugar branches as a novel class of cluster glycosides. The apparent association constant of wheat germ agglutinin (WGA) with poly[3-(N-acryloylamino)propyl 2-acetamido-2-deoxy-beta-D-glucopyranoside] was determined by measuring the change in fluorescence intensity produced by various concentrations of polymeric ligand and found to be approximately 10(8) M(-1). Addition of the cluster type GlcpNAc polymer to WGA induced much greater enhancement of the fluorescence intensity and a significant blue shift of the fluorescence emission maximum of WGA than did addition of the low-density GlcpNAc polymer derived from n-pentenyl glycoside.