A naturally occurring electron resonance. spectrum has been detected in raw wool and in exhaustively scoured wool fibers and cloth. A similar resonance has been found in silk fibers. These spectra consist of a single line about 10 gauss wide centered at g = 2.003. Paramagnetic impurities in wool give rise to another much broader resonance which varies in intensity, g-value. and line width. The origin and nature of these resonances are discussed.