This investigation aimed to develop and validate a simultaneous method for the determination of atorvastatin, ezetimibe and fenofibrate by RP-HPLC and its degradation studies. The analytical method was carried out using Waters X-Bridge C18 250 x 4.6 mm i.D., 5 m. A 32 factorial design was applied to simultaneously analyze the independent variables and response. Batch optimization was done on the basis of numerical optimization and Derringer Desirability approach, respectively. The optimized mobile phase consists of acetonitrile: water: methanol having a ratio of 60:10:30v/v/v was performed at a flow rate of 1ml.min. The pH of the mobile phase was adjusted up to 3 with orthophosphoric acid. The detection carried out at a observed wavelength of 233 nm. Assay for the marketed formulation was carried out and % assay for atorvastatin, ezetimibe and fenofibrate was found to be 100.1 %. 99.9% and 99.9% respectively. Different degradation studies were carried out using 0.1N HCl, 0.1N NaOH, 1%H2O2, photo degradation and thermal degradation. The method was validated according to ICH guidelines which include accuracy, precision, specificity, linearity, and analytical range.