A simple, precise and stability-indicating RP-HPLC method was developed for simultaneous quantification of oxycodone (OXCD) and naltrexone (NTRX) in combined dosage form. The developed method was validated with respect to precision, linearity, accuracy, robustness, ruggedness, sensitivity and solution stability. The method was developed with ammonium di hydrogen phosphate buffer (pH 5.0) and acetonitrile in a ratio of 55:45 (v/v) as mobile phase at a flow rate of 1.0 mL/minute over Intersil ODS C18 column (250 mm × 4.6 mm×5μ).The UV detection wavelength was fixed at 235 nm. The column temperature was maintained at ambient temperature. The method showed good linearity with correlation coefficient values of 0.9990 and 0.9994 for OXCD and NTRX. The percent recoveries of the two drugs found within the limits of 98.0–102.0%. The LOQ concentrations of OXCD and NTRX are 0.625 μg/ mL and 0.075 μg/mL, respectively. The LOD concentrations of OXCD and NTRX are 0.3125 μg/mL and 0.0375 μg/mL, respectively. According to ICH guidelines forced degradation study was validated.