Pharmacological alteration of thrombosis is a key aspect of many treatment regimens. Altering the ability of blood to form a thrombus, although therapeutic, is associated with many adverse effects linked to poor perfusion, either because of blood loss or lack of patent vasculature. The nurse has an important role in achieving and maintaining patient safety when a patient is prescribed anti-thrombotic medication. This is accomplished by ensuring timely medication administration, appropriate monitoring, and focused patient education. This chapter reviews the physiological process involved in thrombosis, focusing on coagulation and platelet function. This elucidation provides an understanding of the pharmacological prevention and or treatment of thrombosis while identifying the pharmacokinetics, drug - drug interactions, and possible adverse reactions of anti-thrombotics medications. This information provides a foundation from which practitioners can safely manage common anti-thrombotic therapy in clinical use.