Hydrazinolysis of porcine thyroglobulin glycopeptides and of pineapple stem bromelain (EC 3.4.22.4) permitted the isolation of almost intact carbohydrate chains of these glycoproteins. On the basis of permethylation analyses of the released oligosaccharides after reduction with NaBH4, the core structures of Unit A-type and Unit B-type carbohydrate chains of porcine thyroglobulin were deduced to be Manα1->6(Manα1→3)Manβ1→4GlcNAcβ1→4(Rα1→6)GlcNAc→Asn (Unit A-type, R=H; Unit B-type, R=Fuc), and that of bromelain was found to be Manα1→6(R'1→2)Manβ1→4GlcNAcβ1→4(R1→3)GlcNAc→Asn (R' =Xy1β and R=Fucα, and R =Fucα, or R' =Fucα and R=Xylβ). From these results, it appears that the hydrazinolysis method is applicable to a wide variety of glycoproteins which have an N-glycosylamine linkage between the carbohydrate and peptide moieties, regardless of the type of linkage to the most proximal N-acetylglucosamine residue which is bound to asparagine.