Plasminogen activator inhibitor-1 (PAI-1) is a member of the serine protease inhibitor (serpin) superfamily, which inactivates tissue plasminogen activator (tPA); therefore, increased level of PAI-1 antigen counteracts the anticoagulant effect of tPA and facilitates the fibrin clot formation. Plasma PAI-1 antigen and activity levels are associated with increased body mass index and with features of the insulin resistance syndrome like obesity and diabetes. Visceral adipose tissue produces more PAI-1 than subcutaneous adipose tissue: This increased production of PAI-1 from the visceral adipose tissue is one important link between visceral obesity and cardiovascular disease. Besides visceral adipose tissue, there is mounting evidence that epicardial adipose tissue may be an important source of PAI-1, especially in patients with type 2 diabetes.