This is fragment 195 to 209 amino acid from the early Hong Kong influenza virus A/Aichi/2/68 (X-31). The complete amino acid sequence (328 residues) of variant-A/Aichi/68 HA`1 was compared to A/Memphis/72 haemagglutinins, and the study has revealed several differences in structure. The monosaccharide compositions of the individual carbohydrate units on variant-A/Aichi/68 haemagglutinin differ from those of the corresponding units in variant-A/Memphis/72 haemagglutinin.