A simple and rapid reverse phase-high performance liquid chromatography (RP-HPLC) method was developed and validated for quantitative determination of Trametinib in bulk drug and marketed formulations. Trametinib was analyzed by using reverse phase Develosil ODS HG-5 RP C₁₈, 5µm, 15cm x 4.6mm i.d., with mobile phase consisting of Methanol and Phosphate buffer (0.02M, pH-3.6) in the ratio of 45:55%v/v. The flow rate was set 1.0 ml/min and the analysis was performed at wavelength 255 nm using Ultra Violet (UV) detector at ambient temperature. The method was validated according to Guidelines of ICH. The retention time for Trametinib was around 3.254 minutes. The calibration curves were linear (r 2- 0.9995) over a concentration range from 12.0 to 28.0µg/ml. Limit of detection (LOD) and Limit of quantitation (LOQ) were found to be 5.004µg/ml and 15.164µg/ml respectively. The developed method was successfully applied to estimate the amount of Trametinib in bulk form and Marketed Pharmaceutical Dosage form.