Adrenaline, noradrenaline and dopamine have been quantified by direct injection of plasma and urine in a liquid chromatographic system comprising three columns, one packed with a boronic acid gel and two with reversed-phase material. The catecholamines were selectively adsorbed on the boronic acid gel and separated by ion-pair chromatography on the reversed-phase columns. Dopamine was detected by coulometry, while noradrenaline and adrenaline were detected by fluorimetry as trishydroxyindoles after post-column coulometric oxidation and alkaline rearrangement. The reaction rate constants of the post-column reactions were determined by a flow injection analysis approach. Limits of detection were 0.04, 0.05 and 1.6 pmol for noradrenaline, adrenaline and dopamine, respectively. Endogenous plasma levels of noradrenaline and adrenaline could be quantified with a precision (RSD) of 2–4%.