A simple, rapid, and precise method was developed for the quantitative simultaneous determination of telmisartan and hydrochlorothiazide in combined pharmaceutical dosage form. Chromatographic separation of two drugs was achieved on an ACE 5 C18 25-cm analytical column using buffer-acetonitrile (60:40, v/v) of pH 5.5, adjusted with acetic acid. The buffer used in mobile phase contains 50mM ammonium acetate in double distilled water. The instrumental settings were: flow rate, 1 mL/min; column temperature, 30 degrees C; and detector wavelength, 260 nm. The internal standard method was used for the quantitation of the ingredients of this combination. Methyl paraben was used as an internal standard. The method was validated for linearity, accuracy, precision, limit of detection, limit of quantification, and robustness. The calibration curve shows excellent linearity over the concentration range for telmisartan and hydrochlorothiazide were 10-150 and 5-75 microg/mL, respectively. The correlation coefficient for telmisartan and hydrochlorothiazide were 0.9999. The relative standard deviation for six replicate measurements in two sets of each drug in tablets are always less than 2%. The proposed method was found to be suitable and accurate for quantitative determination of telmisartan and hydrochlorothiazide in pharmaceutical preparation and it can be used for the quality control of formulation products.