A precised and reproducible stability indicating RP-HPLC method was developed for the simultaneous estimation of hydrochlorothiazide, ramipril and losartan potassium in plasma by using Symmetry C18 column (4.6 x 150mm, 5Pm, Make: Hypersil) in an isocratic mode. The drug was spiked in the plasma and extracted with mobile phase by precipitation method. The mobile phase was consisted of potassium dihydrogen phosphate (KH2PO4) and acetonitrile [HPLC Grade] in the ratio of 68:32 (% v/v). The detection was carried out at 210 nm. The percentage mean recoveries of hydrochlorothiazide, ramipril and losartan potassium were found to be 98.21-101.13, 98.82-100.93 and 99.69-100.98 percentage respectively. This reveals that the method is quite accurate. The method was linear over the concentration range for hydrochlorothiazide 12.5-32.5, ramipril 1.25-3.25 and losartan 50.0 -130.0 Pg/mL. The percentage relative standard deviation for inter-day and intra-day precision was found to be within limits. The lower limit of quantification was found to be 0.647, 1.283 and 2.647 µg/mL for hydrochlorothiazide, ramipril and losartan respectively. The percentage relative standard deviation obtained for the drugs spiked in plasma for stability studies were less than 2 %. The validation of method was carried out utilizing ICH-guidelines.