An accurate, sensitive, selective and precise stability indicating Isocratic RP-LC method and UV-visible Spectroscopic method were developed for the quantitative determination of enzalutamide in bulk and synthetic mixture. The HPLC was carried out by reversed-phase technique on Sun fire C18, 5 µm column with mobile phase containing methanol: water (70:30). The flow rate was 1.0 ml/min and effluents were monitored at 234 nm with help of photodiode array (PDA) detector. UV spectroscopic determination was carried out at an absorption maximum of 234 nm using methanol as a solvent. The linearities were in the range of 4-14 µg/ml for UV-visible spectroscopic method and 0.03-20 µg/ml for RP-LC method, respectively. Validation of proposed method has been carried out with respect to linearity, accuracy, precision, specificity and robustness. Stock solution of EZA was subjected to acid and alkali hydrolysis, chemical oxidation, dry heat degradation and photolytic degradation and quantification has been carried out by proposed RP-LC method. Enzalutamide is susceptible to acidic and basic hydrolysis while it is stable towards chemical oxidation, dry heat and photolytic stress condition. Statistical comparison of both the method has been carried out by Student’s F-test showed no significant difference between the results obtained by the two methods. Due to sensitivity, rapidity and accuracy of methods, we believe that the both proposed methods will be useful for the routine quality control analysis and quantification of drug in bulk and from synthetic mixture.