From injury through healing, thrombin has several important functions in blood clotting, subsequent clot lysis, and tissue repair. These include edema, inflammation, cell recruitment, cellular releases, transformations, mitogenesis, and angiogenesis. Thrombin also participates in disease states, such as venous thrombosis, coronary thrombosis, stroke, and pulmonary emboli, among others and is implicated in atherosclerosis, the growth and metastasis of certain cancers, Alzheimer's disease, and perhaps other conditions. Thrombin must be continually generated to sustain normal and pathogenic processes. This is because of a variety of consumptive mechanisms. Unlike other activated factors in thrombotic and fibrinolytic pathways, and because thrombin promotes its own generation (feedback and cellular activation), thrombin is a primary target for therapeutics. Besides recombinant hirudins, Argatroban (Novastan) and Bivalirudin (Hirulog) are promising thrombin-directed inhibitors for antithrombotic intervention.