A new simple isocratic RP-HPLC method was developed for the simultaneous estimation of Metformin Hydrochloride and Sitagliptin Phosphate in tablet formulation. The separation was achieved on SUPELCO C-18 analytical column (150cm ×4.6mm I.D., 3μm particle size) in isocratic elution mode with the mobile phase consisting of 10mM Potassium dihydrogen ortho phosphate (pH:3.00): Acetonitrile in the ratio of 65:35 v/v and the column was maintained at 25°C. The detection of eluent from the column was detected using UV detector at 256nm and the flow rate was maintained at 1.0 ml/min. The proposed method has permitted the quantification of Metformin Hydrochloride and Sitagliptin Phosphate in the linearity range of 100-300μg/ml and 10-30μg/ml. The method was validated in terms of system suitability, specificity, linearity and precision. The proposed method can be successfully applied in the quality control of bulk and pharmaceutical dosage forms.