This new multi-authored book reviews the current understanding of the role of thrombin in venous and arterial thrombosis and its inhibition in the clinical setting. Heparin, the most widely used antithrombotic, does not effectively regulate thrombin or its formation. Accumulating evidence suggests that other antithrombins are effective in some of the situations where heparin is not. Discussions include the current knowledge on antithrombotic prophylaxis and therapy, from the perspective of the role in thrombin in venous and arterial vascular disease, the limitations of the current anticoagulant therapies, and potential and limitations of newer antithrombins currently being tested in several experimental and clinical settings. Thrombin helps the clinician to better rationalize the use of specific antithrombins in the prevention and management of thrombotic disease and provides the basic scientist with a better understanding of the goals the clinician attempts to achieve with antithrombotic therapy.