The N-terminal and the C-terminal residues of human and horse hair and partially reduced hair have been determined. Aspartic acid, glutamic acid, glycine, serine, threonine, alanine, and valine were identified as N-terminal groups. Aspartic acid, glutamic acid, glycine, serine, threonine, and alanine were identified as C-terminal groups. These are the same N-terminal and C-terminal amino acids as have been found previously for wool and feather keratin.