Polyclonal antisera made against synthetic peptides corresponding to expected tryptic fragments of gamma crystallin have been used to screen tryptic digests of total proteins from cataractous versus normal human lenses. One of these antisera recognizes two peptides that were found in greater amounts from digests of cataractous lenses. These two peptides shared a common sequence that contained an aspartate residue in place of an expected asparagine, suggesting that increased deamidation of this residue had occurred in the human cataractous lensin vivo.