The crystal structure of methyl 4,6- O-benzylidene-2,3-dideoxy-2-[2-(methoxycarbonyl)phenylamino]-3-nitro-β- d-mannopyranoside, C 22H 24N 2O 8, is monoclinic, P2 1, with cell dimensions a = 13.267(4), b = 9.633(4), c = 8.839(3) Å, β = 106.26(2)°, Z = 2. The structure was solved by direct methods, and refined to R(F obs) = 0.056 for 6959 independent reflections measured with MoKα radiation. The configuration of the molecule was confirmed. The pyranoid conformation is 4 C 1 with Q = 0.611 Å, = 8.5°. The dioxolane conformation is close to the ideal chair. The orientation of the anthranilate ring is such that the amine hydrogen atom forms three intramolecular hydrogen-bonds: one major bond to the anthranilate carbonyl oxygen atom, and two minor bonds to the glycosidic oxygen atom and the ring-oxygen atom. The orientation of the anthranilate group is thus fixed such that the angle between the plane of the benzene ring and that of the nitro group is 116°, thereby permitting an intramolecular, CHO hydrogen-bond between the benzene ortho CH and the nitro oxygen atom. This bond is normal to the plane of the nitro group, and is believed to be the source of the color phenomenon that prompted this structure analysis.