A new, simple, precise, rapid, selective and stability reversed-phase high performance liquid chromatographic (RP-HPLC) method has been developed and validated for the simultaneous quantification of Vilanterol and Umeclidinium in pure form and its pharmaceutical dosage form. The method is based on Agilent Zorbax XDB C18(150mm×4.6mm,5μ). The separation is achieved using isocratic elution by Potassium dihydrogen phosphate: Methanol (40:60) v/v, pumped at flow rate 1.0mL/min and UV detection at 235nm. The column is maintained at 25°C throughout the analysis. The total run time is about 6min. The method is validated for specificity, accuracy, precision and linearity, robustness and ruggedness, system suitability, limit of detection and limit of quantitation as per international conference of harmonization (ICH) Guidelines. The method is accurate and linear for quantification of Vilanterol, Umeclidinium between 50 - 150µg/mL and 50 - 150µg/mL respectively. Further, satisfactory results are also established in terms of mean percent- age recovery for Umeclidinium, intra-day and inter-day precision (<2%) and robustness. The advantages of this method are good resolution with sharper peaks and sufficient precision. The results indicate that the method is suitable for the routine quality control testing of marketed tablet formulations. Keywords: Vilanterol and Umeclidinium, RP-HPLC, ICH Guidelines, Accuracy, Precision