A simple, accurate, specific and reliable RP-HPLC method for the simultaneous estimation of Sitagliptin Phosphate and Metformin Hydrochloride in Pharmaceutical dosage form was developed and validated according to currently accepted ICH guidelines of analytical method validation. In the present method, SHIMADZU HPLC with UV detector LC 10 AT VP with analytical column PHENOMENEX Luna (C18) A 100 RP Column, 250 mm x 4.6 mm x 5μm, an injection volume of 20µl was injected and eluted with mobile phase 0.02M Potassium dihydrogen phosphate pH (4.0): Acetonitrile (60:40) pumped at a flow rate of 1.0ml/min. Sitagliptin Phosphate and Metformin Hydrochloride were eluted at 2.718 and 1.925 min. The detection was carried out at a wavelength 252nm. The method was validated for system suitability, linearity, accuracy, precision and robustness of sample solution. The linear ranges for Metformin Hydrochloride and Sitagliptin Phosphate were 20-120μg/mL, 2-12μg/mL respectively with good recoveries i.e. 99.4% to 101.35%. Keywords: Metformin Hydrochloride, Sitagliptin Phosphate, RP-HPLC.