Urokinase (Abbokinase), also called urokinase-type Plasminogen Activator (uPA), is a serine protease (EC 3.4.21.73). The primary physiological substrate is plasminogen, which is an inactive zymogen form of the serine protease plasmin. Activation of plasmin triggers a proteolysis cascade. The participation of Urokinase in thrombolysis or extracellular matrix degradation links it to vascular diseases and cancer.

Urokinase is used as a thrombolytic agent in the treatment of severe or massive deep venous thrombosis, pulmonary embolism, and myocardial infarction.