It was confirmed by zymographic technique that 1 ml of normal human plasma possessed about 0.2 IU of urokinase activity which is a high molecular weight form with a molecular weight of 53,000. Plasma of an acute pancreatitis patient followed by disseminated intravascular coagulation possessed the same amount of urokinase activity as normal plasma, and was confirmed to be composed of two types of urokinase, a high molecular weight form and a low molecular weight form with a molecular weight of 33,000.