Thrombosis is a common cause of various acute cardiovascular diseases including acute coronary syndrome. Antithromotic therapy is widely used in cardiology community even though the vast majorities of cardiologists are not quite familar with the detailed mechanisms of thrombus formation mediated be platelet, inflamatory cells, coagulation cascade, and so on. The clinical evidences obtained from clinical studies, especially clinical trials comparing the efficacy and safety of novel antithrombotic agents vs previously established standard of care, provided the clues to improved the quality of the standard of care antithrombotic therapy for various patient populations. The global clinical trials still are the best way to test the clinical hypothesis. New generation of antithrombotic therapy become novel standard of care only when it showed better efficacy and safety as compared to the previously established standard of care in the clinical trial. These hypothesis testing clinical trials were conducted on the globe assuming the homogeniety of the risk of thrombotic and bleeding events across the globe. So far, it is hard to clarify the best suitable antithrombotic therapy for individual patients in a scientific manner. Various novel antithrombotic therapies became novel standard of care in various cardiovascular diseases within previous 10 years. The platelet P2Y₁₂ ADP receptor blockers are widely used in patients with acute coronary syndrome. Various orally available specific inhibitors for coagulation factor Xa are also used widely for prevention of thrombotic stroke in patients with atrial fibrillation. However, the global clinical trial is not a perfect way to provide scientific evidence for the use of antithrombotic therapy for all individual patients. Indeed, reduced doses of antithrombotic agents not tested in the global trials are recommended in some countries to avoid serious bleeding events. These reductions of doses are recommended based upon the results from the country or region specific clinical trials. The scientific values of these region/country specific clinical trials are limited. The clinical trials are helpful to improve the standard of care for specific patients populations. However, each physician should take care of their individual patients. In the clinical practice, physicians made their decision based upon their intuitive prediction of the future risk of thrombosis and bleeding in individual patients. These intuitive decisions made by physicians are not scientific. Recent progress in the high-performance computer and information technology enable to provide scientific evidences for personalized medicine in both inductive and deductive manner. Accordingly, developments of novel antithrombotic therapies in Cardilogy are still exciting area of research in both basic and clinical approach.