Glycophorin A isolated from human erythrocytes contains one asparagine-linked sugar chain in one molecule. This sugar chain was successfully released as an oligosaccharide fraction by hydrazinolysis. The oligosaccharide fraction was separated into four components (N, A-1, A-2', and A-2) by paper electrophoresis. Complete structures of the major acidic oligosaccharides (A-1 and A-2) were elucidated by sequential exoglycosidase digestion in combination with methylation study and periodate oxidation as follows: NeuAc alpha 2 leads to 6Gal beta 1 leads to 4GlcNAc beta 1 leads to 2Man alpha 1 leads to 6(3) [Gal beta 1 leads to 4GlcNAc beta 1 leads to to 2Man alpha 1 leads to 3(6)] (GlcNAc beta 1 leads to 4)Man beta 1 leads to 4GlcNAc beta 1 leads to 4(Fuc alpha 1 leads to 6)GlcNAc and NeuAc alpha 2 leads to 6Gal beta 1 leads to 4GlcNAc beta 1 leads to 2Man alpha 1 leads to 6(NeuAc alpha 2 leads to 6Gal beta 1 leads to 4GlcNAc beta 1 leads to 2Man alpha 1 leads to 3) (GlcNAc beta 1 leads to 4)Man beta 1 leads to 4GlcNAc beta 1 leads to 4(Fuc alpha 1 leads to 6) GlcNAc. The abbreviations used are: NeuAc, N-acetylneuraminic acid; GlcNAc, N-acetylglucosamine; Fuc, fucose.