Aβ-variant hemoglobin, first misjudged as a marked elevation of Hb A1, was found in a 68-year-old Japanese female with diabetes mellitus. This hemoglobin was isolated by Bio-Rex 70 chromatography combined with chromatofocusing, and was found to be Hb Hope,β136(H14)Gly→Asp, by classical and high performance liquid chromatographic peptide mapping techniques.Intrinsicoxygen affinity of this hemoglobin was approximately one-third as compared with that of Hb A0.his property was still observed in the constituentβsubunits isolated. Effects of such allosteric effectors as H+(at a fixed concentration of Cl−), anion (Cl−), 2,3-diphosphoglycerate and carbon dioxide were more or less depressed. Among others, a marked reduction in the carbamate effect should be noted in a structural interpretation of the functional modifications. Subunit cooperatlvity, on the contrary, was not different from that in Hb A0(n= 2.8-2.9). Explanation of these altered functions were attempted on the basis of the altered structure. The reduced stability of Hb Hope is also described.