Nitrous acid deamination of 2-amino-1,6-anhydro-2-deoxy-β- D-glucopyranose ( 1) in the presence of weakly acidic, cation-exchange resin gave 1,6:2,3-dianhydro-β- D-mannopyranose ( 3) and 2,6-anhydro- D-mannose ( 6), characterized, respectively, as the 4-acetate of 3 and the per- O-acetylated reduction product of 6, namely 2,3,4,6- tetra- O-acetyl-1,5-anhydro- D-mannitol, obtained in the ratio of 7:13. Comparative deaminatior of the 4- O-benzyl derivative of 1 led to similar qualitative results. Deamination of 3-amino-1,6-anhydro-3-deoxy-β- D-glucopyranose gave 1,6:2,3- and 1,6:3,4-dianhydro-β- D-allopyranose ( 13 and 16), characterized as the corresponding acetates, obtained in the ratio of 31:69, as well as the corresponding p-toluenesulfonates. Deamination of 4-amino-1,6-anhydro-4-deoxy-β- D-glucopyranose and of its 2- O-benzyl derivative gave the corresponding 1,6:3,4- D- galacto dianhydrides as the only detectable products. 2,5-Anhydro- D-glucose, characterized as the 1,3,4,6-tetra- O- acetyl derivative of the corresponding anhydropolyol, was obtained in 39% yield from the same deamination reaction performed on 2-amino-1,6-anhydro-2-deoxy-β- D- mannopyranose ( 24). In 90% acetic acid, the nitrous acid deamination of 24, followed by per- O-acetylation, gave only 1,3-4-tri- O-acetyl-2,5-anhydro-α- D-glucoseptanose. In the case of 1,6-anhydro-3,4-dideoxy-3,4-epimino-β- D-altropyranose, only the corresponding glycosene was formed, namely, 1,6-anhydro-3,4-dideoxy-β- D- threo--hex-3-enopyranose.