An approach of forced degradation study was successfully applied for the development of a stability-indicating assay method for simultaneous estimation of Etofylline and Theophylline in a formulation in the presence of its degradation products. The method showed adequate separation of Etofylline and Theophylline from their associated main impurities and degradation products. Separation was achieved on an YMC Pack-ODS-AQ, 150 x 4.6 mm the mobile phase 10mM Potassium Di-Hydrogen Phosphate : Acetonitrile (90:10) pH-4.5 with ortho phosphoric acid buffer flow rate of 1 mL/min and UV detection at 272 nm. Comprehensive stress testing of Etofylline and Theophylline Rt= 6.4 & 5.2 min was according to the International Conference on Harmonization (ICH) guideline Q1A (R2). The method was validated in terms of system suitability, precision, linearity, accuracy, robustness, ruggedness, LOD, LOQ and solution stability