Good quality polarized Raman spectra of a single wool fiber and an intact feather barbule are presented. The intensity ratio of the โฃ-helix component of the amide I band measured parallel and perpendicular to the wool fiber axis was 0.39 ฯฎ 0.05. This is consistent with theoretical predictions based on orientational calculations using the normal Raman polarizability tensor for an โฃ-helical amide I band where the protein strands are aligned roughly parallel with the fiber axis. However, the depolarized spectral intensity of the โฃ-helix mode was greater than expected. For the feather barbule, despite high quality spectra, a unique orientation of the โค-sheet structure could not be determined using the Raman intensity ratios of the amide I band alone. Using previously developed methods, the protein chains were found to be oriented between 60 and 90ยฐfrom the long axis of the barbule compared to an angle of 51ยฐc alculated from polarized IR spectra of the same barbule. The Raman tensor methods for the determination of protein orientation in these fibers was found to be constrained by the complexity of the materials and the limitations of the band fitting methods used to apportion the intensity among the various vibrational modes of their spectra. Other advantages and limitations of polarized Raman microscopic methods of structural determination are discussed.