The FT-Raman spectra of mammalian and avian keratotic biopolymers have been recorded, including bull's horn, cat's claw, bird's feather quill, pheasant's beak and compared with the hard keratinous tissue, human nail and callus. Although there were similarities in all the spectra. particularly in the v(CH) stretching region, the 1450-1100 cm-1 region exhibited some differences ascribed to intramolecular skeletal backbone conformational changes. Of particular significance for human, mammalian and avian samples in the 1000-400 cm-1 wavenumber region were differences in the structurally important v(SS) and v(CS) bands, near 500 cm-1 and 630 cm-1 respectively. The amide I and III modes near 1650 and 1250 cm-1 respectively, demonstrate that the mammalian keratins studied exist predominantly in the alpha-helical conformation, whereas the avian keratins adopt the beta-sheet structure as the dominant conformation.