The purpose of the investigation was to develop a new RP-HPLC Method for estimation of Aprepitant in pharmaceutical dosage forms. Chromatography was carried out on an Kromosil C18 column (4.6 x 250mm, 5μ particle size) with a isocratic mobile phase composed of 0.1% Perchloric acid, Acetonitrile (80:20v/v) at a flow rate of 1.1 mL/min. The column temperature was maintained at 30°C and the detection was carried out using a PDA detector at 210 nm. Validation parameters such as system suitability, linearity, precision, accuracy, specificity, limit of detection (LOD), limit of quantification (LOQ), Stability of sample and standard stock solutions and robustness were studied as reported in the International Conference on Harmonization guidelines. The retention time for Aprepitant was 3.429 min. The percentage recovery of Aprepitant was 101.01%. The relative standard deviation for assay of capsule was found to be less than 2%. The Method was fast, accurate, precise and sensitive hence it can be employed for routine quality control of capsules containing drugs in quality control laboratories and pharmaceutical industries.