A gradient reversed phase high performance liquid chromatography (RP-HPLC) method has been developed and validated for the determination for eight related substances of Dabigatran Etexilate Mesylate. The successful chromatographic separation of Dabigatran Etexilate from its related substances was achieved on octadecyl silane chemically bonded to porous silica particles stationary phase i.e Inertsil ODS-4, 250mm x 4.6mm, i.d., 5m column maintained at temperature at 25°C by using phosphate buffer pH 3.0 and acetonitrile as mobile phases A & B respectively. Wavelength for UV detection: 220nm, flow rate: 1.0ml/min and Injection volume: 10μl. The performance of the method was validated according to the ICH guidelines for specificity, linearity, accuracy, precision, limit of quantification, limit of detection robustness and ruggedness and also DEM was subjected to stress conditions of thermal, hydrolysis, humidity, peroxide and photolytic to observe the degradation products. Limit of detection of impurities was in the range of 0.007%–0.008% indicating the high sensitivity of the developed method. The experiment results are given in detailed in this paper.