Pleural Effusion (PE) is defined as collection of fluid in pleural space and classified into two categories of exudative and transudative PE. PE is the result of a wide range of medical conditions including infection, malignancy, trauma, collagen vascular disease, etc. Coagulation system plays an important role in pleural diseases. Understanding the pathophysiological mechanisms of the coagulation and pleural disorders may open possibilities for novel diagnostic and therapeutic approaches. Several studies have reported that exudative pleural effusion is associated with enhanced local fibrinolytic activity. Thus, D-dimer level; a marker of solid phase fibrin dissolution; was found to be high in patients with exudative pleural effusion. The D-dimer is a product of fibrin degradation that is formed by the sequential action of enzymes of coagulation cascade. Coagulation cascade plays an important role in pleural diseases and several studies have reported that TPE is associated with enhanced local fibrinolytic activity.