Graphite furnace atomic absorption spectrometry (GFAAS) is used to analyze a variety of biological materials. Conventional single element determinations as well as multielement determinations made on the SIMAAC are discussed. Four sample preparation methods were used to prepare samples for GFAAS including: direct analysis of liquids, wet ashing, dry ashing, and slurry preparation. Results from analyses of a wide variety of materials are presented.