Extracting a series of amino acids from fossil collagen makes it possible to compare chemically well-characterized molecules from one bone sample, both chemically and by isotopic analysis. Thus, the integrity of collagen samples and possible contamination can be checked. Describes the routine high-performance liquid chromatographic extraction of five amino acids: glycine, hydroxyproline, glutamate, threonine, and alanine. Humates are eliminated during the extraction, which can be monitored continuously.