Hemostasis refers to body's natural reaction that stops bleeding and initiates the repair of an injury. There are three principal steps involved in the mechanism of hemostasis. These include vasoconstriction, platelet plug formation and blood coagulation. Thrombosis is a condition that develops when blood clots block the blood vessels. It is of two main types, namely, venous thrombosis and arterial thrombosis. Some common causes of thrombosis are obesity, certain medicines, disease or injury to the leg veins, and autoimmune disorders. Its treatment includes medicines such as blood thinners to prevent blood clots. It also involves the placement of stents or catheters to reopen the blockage in the vessels. Losing weight and quitting smoking can help in preventing medical complications related to thrombosis. This book outlines the processes of hemostasis and thrombosis in detail. It will also provide interesting topics for research, which the interested readers can take up. The book will prove to be immensely beneficial to students and researchers in the field of hematology.