An imbalance between procoagulant system and regulatory mechanisms can cause excessive fibrin production leading to Thrombosis. These imbalances can be genetic or acquired or due to a combination of both leading to excessive fibrin formation at the site of injury with vessel occlusion and thrombus formation. Major risk factor for arterial thrombosis is atherosclerosis while for venous thrombosis, the risk factors include immobility, surgery, malignancy, hormone therapy, obesity and genetic factors.