The generic versions have the same main component as the original products. But, due to the difference in additives or the level of impurities, it is questionable the the generic versions are completely identical to the original products. Nafamostat mesilate has been widely used as an anticoagulation in continuous renal replacement therapy (CRRT) with hemorrhagic diathesis. In this study, we performed comparison of circuit patency and exchange rates between the original products and the generic versions of Nafamostat mesilate in acute kidney injury patients receiving continuous renal replacement therapy We have conducted retrospective studies to compare the original product of nafamostat mesilate (n=732) with the generic version (n=328) on the CRRT running time. CRRT fiter life time of the generic version group was shorter than that of original product group although that was not significantly. When generic versions of nafamostat mesilate are adopted in a hospital formulary, it must be emphasized that the effect these versions may be not completely identical to that of the original products.