The development and validation of a simple, rapid, precise and accurate RP-HPLC has been described for the simultaneous assessment and invitro dissolution of Olmesartan (OLM), Amlodipine (AML) and Hydrochlorothiazide (HCTZ) in their combined dosage forms. Separation was performed on Inertsil ODS-3 column (C18, 150 mm x 4.6 mm, 5 μm) using photodiode array (PDA) detection at 255 nm. The mobile phase consisted of phosphate buffer (pH 3.5) and acetonitrile, in a gradient program (time in minutes/acetonitrile %: 0.00/30, 1.00/30, 8.30/70 and 9.00/30) at a 1.3 ml min-1 flow rate. Analytes were perfectly resolved with retention times of 2.59, 4.99 and 7.48 min for OLM, AML, and HCTZ, respectively. Following the recommended procedure, linear calibration graphs extended for 0.20-28.00, 0.05-7.00 and 0.12-17.50 μg ml-1 with detection limits of 0.021, 0.002 and 0.012 μg m;-1 and quantitation limits of 0.063, 0.036 and 0.007 μg ml-1 for the assay and in-vitro drug release of OLM, AML and HCTZ, respectively. In-Vitro dissolution revealed that >96% of the labeled OLM, AML and HCTZ were released from their combined tablets within 20 min. The developed method was validated following the ICH guidelines regarding the system suitability, specificity, linearity, accuracy, precision, and robustness.