hydrochlorothiazide (hct) is a diuretic agent which is shown to be effective in the treatment of hypertension. literature reports have demonstrated that urinary excretion data may be used to assess the bioavailability of various formulations containing this thiazide. also hct consumption by the athletes is one of the drugs which should be regulated by world anti-doping agency (wada), because of this fact that urinary excretion of this agent may be a sign of other stimulant consumptions before competitions . so proposing a fast and sensitive quantification method is very important in medicinal aspects. in the present study, performance of the dispersive liquid-liquid microextraction (dllme) technique for determination of hydrochlorothiazide in urine samples was evaluated and validated. experimental design through a 2(7-3) fractional factorial design was used during method optimization. among the seven factors and their intractions, seven of them as the extraction solvent, volume of extraction solvent and the urine ph was considered to be significant through pareto charts and anova results.under optimal condition, linear range in 0.1-50 mgl -1 with (r2=0.998) was obtained and lod, loq, intraday rsd and between day was 15.60 ?gl-1, 51.50 ?gl-1, %0.59 and %7.49 respectively. the matrix effect was studied and it was shown that the performance of the method was scarcely affected by the endogenous compounds presented in urine samples. the proposed method was validated on different