Various methods are currently used for determining taurine in biological samples, including ion-exchange chromatography [1-3] and, more recently, reversed-phase high-performance liquid chromatography (HPLC) [4-8]. These techniques usually require long operating times or afford low sensitivity and are, therefore, of little interest for routine analysis. In this paper an HPLC method that allows the rapid, precise and accurate determination of taurine in biological samples is presented. The method involves the extraction of taurine from plasma or urine samples with trichloroacetic acid, pre-column derivatization with 7-chloro-4-nitrobenz-2-oxa-1,3-diazole (NDB-C1) and separation of the taurine derivative by anion-exchange HPLC with isocratic elution and fluorimetric detection.