Human skin offers potential advantages for the administration of therapeutic agents for both local and systemic use. However, in studies of transdermal drug delivery, problems with the supply, storage, and use of human tissue have encouraged workers to seek alternative animal materials to model drug diffusion across human skin. We obtained Fourier transform Raman spectra from mammalian (human and pig) and reptilian (snake) skins, and considered structural dissimilarities in the light of differences observed in the diffusion of drugs across the tissues.