A simple, sensitive, selective and stability indicating UPLC method has been developed for the quantitative determination of potential impurities of allopurinol active pharmaceutical ingredient. Allopurinol, its five impurities and degradation products were separated efficiently by using the mobile phase consisted of sodium perchlorate (10 mM, pH 3.0)and acetonitrile on a HSS T3P stationary phase in gradient elution profile. Forced degradation study confirmed that the newly developed method was specific and selective to the degradation products. The newly developed UPLC method was validated according to ICH guidelines considering five impurities to demonstrate specificity, precision, linearity, accuracy and stability indicating nature of the method. Regression analysis showed correlation coefficient value greater than 0.99 for allopurinol and its five impurities. Detection limit of impurities was in the range of 0.002–0.006% indicating the high sensitivity of the newly developed method. Accuracy of the method was established based on the recovery obtained between 91.7% and 106.6% for all impurities.