All patients with mechaniscal prosthetic heart valves require. some form of prophylaxis Experience in patients without anti-thrombotic prophylaxis has been devastating. This is a case report of a young patient with double Bjork-Shiley mechanical prosthetic heart valves who went. without anticoagulation drugs for nine years without any problem in this period. This case emphasizes the importance of multiple factors that affect the coagulation cascade in individualized patients.