A method for the separation and determination of ascorbic acid (AsA) and erythorbic acid (ErA) in animal tissues is described. It employs high-performance liquid chromatography on a LiChrosorb-NH2 column in conjunction with a mixture of acetonitrile, acetic acid and water as an eluant. Application of the method, which is sensitive, rapid and simple, to the analyses of AsA and ErA in animal tissues such as liver, adrenals, spleen, kidneys and heart gave satisfactory results. Dehydro-AsA and dehydro-ErA in rat liver could be determined after reduction with H2S. The method was shown to be useful for the routine analyses.