SERPINE1 and Stroke: To better understand the role of PAI‐1 in the outcome of stroke thrombolytic therapy, in the present study, we measured PAI‐1 activity and antigen levels during the course of thrombolysis in a cohort of consecutive acute ischemic stroke patients and studied the association of PAI‐1 levels and PAI‐1 4G/5G polymorphism with the outcome and safety of therapy.