The present paper describes the development of a st ability indicating reverse phase liquid Chromatogra phy (RPLC) method for Sitagliptin phospahte in the presence of its impurities and degradation products generated from forced decomposing studies. The drug substance was subject ed to stress conditions of hydrolysis, oxidation, U V and thermal degradation. The degradation of Sitagliptin was observed under acid, base and oxidative hydrol ysis .The drug was found to be stable to other stress conditi ons attempted. Successful separation of the drug fr om the synthetic impurities and degradation product formed under stress conditions was achieved on a symmetry shield C18 column, 150mm, 4.6mm, 3.5μ using a mixture of 0.3% perchloric acid and methanol (70:30, v/v) as m obile phase. The developed HPLC method was validated with respect to linearity, accuracy, precision, specifi city and robustness. The developed HPLC method is to determi ne the assay of Sitagliptin phosphate and can be us ed to evaluate the quality of regular production samples. It can be also used to test the stability samples of Sitagliptin phosphate.