Two L-arabino-D-galactan-containing glycoproteins having a potent inhibitory activity against eel anti-H agglutinin were isolated from the hot saline extracts of mature radish leaves and characterized to have a similar monosaccharide composition that consists of L-arabinose, D-galactose, L-fucose, 4-O-methyl-Dglucuronic acid, and D-glucuronic acid residues. The chemical structure features of the carbohydrate components were investigated by carboxyl group reduction, methylation, periodate oxidation, partial acid hydrolysis, and digestion with exoand endo-glycosidases, which indicated a backbone chain of (l-+3)-linked P-Dgalactosyl residues, to which side chains consisting of a-(1+6)-linked D-galactosyl residues were attached. The a-L-arabinofuranosyl residues were attached as single nonreducing groups and as O-2-or 0-3-linked residues to O-3 of the P-D-galactosyl residues of the side chains. Single cu-L-fucopyranosyl end groups were linked to O-2 of the L-arabinofuranosyl residues, and the 4O-methyl-P-D-glucopyranosyluronic acid end groups were linked to D-galactosyl residues. The 0-cY-L-fucopyranosyl-(l-2)-a-L-arabinofuranosyl end-groups were shown to be responsible for the serological, H-like activity of the L-arabino-D-galactan glycoproteins. Reductive alkaline degradation of the glycoconjugates showed that a large proportion of the polysaccharide chains is conjugated with the polypeptide backbone through a 3-0-D-galactosylserine linkage.