Abstract: This study deals with the effect of different chemical modifying agents on the mulberry seed protein, namely MSL-1 and MSL-2, to obtain information on the structure-function relationship of these lectins. Mulberry seed lectins, MSL-1 and MSL-2, having specificity for D-galactose were subjected to various chemical modification in order to obtain information about the amino acid residues responsible for their carbohydrate binding property. The modifying reagents used are mild and very much selective for modification of specific groups. Modification of tyrosine, histidine and thiol, groups led to a complete or significant loss of their activities, indicating the involvement of these amino acid residues in the saccharide binding property of the lectins. However, modification of lysine, arginine and trypotophan residues had no such noticeable effect on the biological activities of these two lectins. These findings are very similar to those reported for other lectins that bind D-galactose and also fit the general trend in other lectins.