A stereospecific method of analysis of racemic taxifolin (+/-3,5,7,3',4'-pentahydroxyflavanone) in biological fluids is necessary to study pharmacokinetics and disposition in fruit and herbs. A simple high-performance liquid chromatographic method was developed for the determination of all four taxifolin enantiomers. Separation was achieved on a Chiralcel(R) OJ-RH column with UV detection at 288 nm. The standard curves in serum were linear over a range of 0.5-100.0 microg/mL for each enantiomer. The mean extraction efficiency was >88.0%. Precision of the assay was <15% (CV), and was within 12% at the limit of quantitation (0.5 microg/mL). The bias of the assay was <15%, and was within 6% at the limit of quantitation. The assay was successfully applied to stereospecific disposition of taxifolin enantiomers in rats and to the quantification of taxifolin enantiomers in tu fu ling (Rhizoma smilacis glabrae) and apple (Malus x domestica).