Electron-induced vibrational spectra of four poly(amino acid)s-poly-alanine, poly-leucine, poly-methionine, and poly(benzyl-aspartate)-have been recorded. After discussing the surface sensitivity of the technique and the excitation mechanisms of the molecular vibrations, it is concluded that high resolution electron energy loss spectroscopy (HREELS) spectra are dominated by vibrational bands fingerprinting the polymer sidechains. From these observations, suggestions are made on the molecular conformation at the surface of these poly(amino acid)s films.