The synthesis of four GlcNAc(β1→4)Glcdisaccharides containing 2‐O‐acetyl and/or 6‐sulfate groups was performed in high yields with total 1,2‐trans stereoselectivity. These disaccharides were evaluated as candidates for insect chitinaseinhibition and aphicidalactivity. All the compounds prepared displayed physiologicaleffects on M. persicae aphids; however, the inhibition of chitinases of different