The O-polysaccharide was isolated from the lipopolysaccharide of Cellulophaga tyrosinoxydans and studied by chemical analyses along with H-1 and C-13 NMR spectroscopy, including 2D H-1, H-1 COSY, TOCSY, ROESY, H-1, C-13 HSQC, HMBC and H2BC experiments. The following new structure of the O-polysaccharide of C. tyrosinoxydans containing L-fucose (Fuc), N-acetyl-D-glucosamine (GlcNAc), 4-acetamido-4,6-dideoxy-D-glucose (Qui4NAc) and two L-rhamnose residues (Rha) was established: [GRAPHICS] -> 4)alpha-L-Fucp-(1 -> 3)-beta-D-GlcpNAc-(1 -> 3)alpha-L-Rhap-(1 -> 2)-alpha-L-Rhap-(1 -> (C) 2015 Elsevier Ltd. All right reserved.