A method based on capillary electrophoresis with end-column electrochemical detection (HPCE-ED) was developed for the determination of the diuretics of hydrochlorothiazide (HCT) and triamterene (TAT) simultaneously. The detection electrode was a 300 microm carbon disc electrode at a working potential of +1.1 V versus Ag/AgCl electrode. The two analytes could be well separated within 8 min in a 50 cm long capillary at a separation voltage of 24 kV with a 10 mmol/L phosphate buffer (pH 7.5). Under optimum conditions, the current response was linear over about two orders of magnitude with detection limits (S/N = 3) of 0.29 and 0.25 mg/L for triamterene and hydrochlorothiazide, respectively. The proposed method was successfully applied to determine the synthetic urine and real pharmaceuticals samples. The recoveries were found to be in the range of 93.5%-97.2%.