A new method for the surface modification of nonporous glass beads (average diameter, 6 mum), which characterized by formation of a 1,3-thiazolidine ring between L-cysteine linkers on the glass bead and reducing ends of chitosan, has been developed. gamma-Aminopropyltriethoxysilane (APES)-treated glass bead was first subjected to condensation with an L-cysteine derivative, L-4-carboxy-3-formyl-2,2-dimethylthiazolidine (CFMT), in the presence of water-soluble carbodiimide hydrochloride (WSC) and HOBt. After deprotection by diluted hydrochloric acid, the glass beads with activated cysteine linkers on the surface were treated with reducing chitosan in aqueous acetic acid solution at room temperature. The maximum content of chitosan immobilized on the glass beads estimated by acidhydrolysis and subsequent glucosamine analysis by Svennerholm method after was 0.73% (w/w). This was obtained by using chitosan having an average molecular weight of 14 kD. Model reactions of the cysteine derivatives with reducing chitosan were also performed and the product was examined by IR and NMR spectroscopy to verify the linkage between cysteine and chitosan.