Abstract An α- l -fucosidase from porcine liver produced α- l -Fuc-(1→2)-β- d -Gal-(1→4)- d -GlcNAc (2′-O-α- l -fucosyl-N-acetyllactosamine, 1) together with its isomers α- l -Fuc-(1→3)-β- d -Gal-(1→4)- d -GlcNAc (2) and α- l -Fuc-(1→6)-β- d -Gal-(1→4)- d -GlcNAc (3) through a transglycosylation reaction from p-nitrophenyl α- l -fucopyranoside and β- d -Gal-(1→4)- d -GlcNAc. The enzyme formed the trisaccharides