A reversed-phase high performance liquid chromatographic (HPLC) procedure, using fluorescence detector, is outlined for the single and quantitative determination of trace amounts of amino acids in the ng 1(-1) by pre-column derivatisation. The optimisation of the operating conditions and possible separation mechanism for different amino acids in the chromatographic column am discussed. The fluorescence detection of the derivative has been a great advantage over the UV-detection system. The method can be used, however for the rapid determination of amino acids in complex biological samples.