A rapid and simple method for the determination of taurine (2-aminoethanesulphonic acid) in complex samples is described. It is based on the HPLC separation of the dinitrophenyl (DNP) derivative of taurine. The reaction conditions are selected to allow complete derivatization of taurine within 15 min. DNP-taurine samples are stable for at least 3 days. DNP-taurine was separated by reversed-phase liquid chromatography within 12 s. The recovery of taurine was 102 +/- 3% (S.D. = 2.5%, n = 6) and the detection limit was 10 pmol for taurine (signal-to-noise ratio of 10). The method was applied to the determination of taurine levels in different samples including marine products, infant formulas and fermentation media of different bacterial species.