The present paper describes the development of a stability indicating reverse phase liquid Chromatography (RPLC) method for Finasteride in the presence of its impurities and degradation products generated from forced decomposing studies. The drug substance was subjected to stress conditions of hydrolysis, oxidation, UV and thermal degradation. The degradation of Finasteride was observed under oxidative hydrolysis .The drug was found to be stable to other stress conditions attempted. Successful separation of the drug from the synthetic impurities and degradation product formed under stress conditions was achieved on a Symmetry C18 column using a mixture of water and Acetonitrile (64:34, v/v) as mobile phase. The developed HPLC method was validated with respect to linearity, accuracy, precision, specificity and robustness. The developed HPLC method to determine the related substances and assay determination of Finasteride can be used to evaluate the quality of regular production samples. It can be also used to test the stability samples of Finasteride.