The N-terminal amino acid sequences of the hemopexins purified from the plasma of rat, rabbit and chicken were compared with each other and with that of human hemopexin. Although the N-terminal sequences differ among these species, residues 2, 3 and 14 are identical in all four hemopexins. Ten of the first 28 residues are identical in all but the chicken protein. When introducing gaps into the sequence, a much greater homology is observed between the human and rat or rabbit hemopexins (60%) than when the sequences were compared directly (40%).