Full-length sequencing of the thrombomodulin (TM) gene was obtained in 20 patients with premature acute myocardial infarction (AMI). Clinically relevant polymorphisms were identified and further evaluated in 145 patients with premature AMI and 143 controls. Despite the fact that TM promoter G-33A and C1418T polymorphisms are common in the Chinese population, the association between G-33A mutation and premature AMI indicates that we must focus on promoter G-33A polymorphism rather than C1418T polymorphism in terms of the role of TM gene mutation on premature AMI.