AbstractNon‐enzymatic glycation of protein is a chemical modification reaction often found in human metabolism. Glycated hemoglobin (HbA1c) has been used as a model protein for studying non‐enzymatic glycation because of its biological significance. Several questions have been raised in the course of studying this important biological reaction. Among them, we have focused on two major questions: 1) Why is the amino‐terminus of the β‐chain of human hemoglobin (HbA) a preferred target and not the amino‐terminus of the α‐chain, since HbA has Val residues in both its amino‐termini? 2) Why do some Schiff base intermediates advance Amadori rearrangement but not others?Since non‐enzymatic glycation is a rather slow process, biochemical analysis is often difficult; a model system which mimics the chemistry of non‐enzymatic glycation with a faster reaction rate has been developed. The model system using glycer‐aldehyde with amino acids or peptides has demonstrated that the presence of a His‐2(β) residue contributes significantly to the formation of HbA1c. Such a positively charged group is found at or near the glycation sites in many other non‐enzymatically glycosylated proteins. Thus, it is feasible to assume a unique role for the positively charged residue in non‐en