The main causes of elevated serum transaminases are various diseases of the liver, and some extrahepatic diseases such as hemolysis can also lead to elevated transaminases. Certain non-disease conditions such as strenuous or prolonged exercise such as running and weight lifting can also be a cause of elevated transaminases. The main causes of significant transaminase elevations [greater than 10 – 15 times the upper limit of normal (ULN)] are acute viral hepatitis, drug-induced liver damage, or ischemic hepatitis. Sometimes, chronic hepatitis B or autoimmune hepatitis can also cause significant transaminase elevations. Other rare causes of significantly elevated transaminases include hepatomegaly, acute Bard-Chiari syndrome, and hepatic artery ligation or thrombosis. In addition, acute bile duct obstruction due to passage of gallstones can also have a transient significant elevation of serum transaminase levels. Zhu Qi, Department of Hepatobiliary Medicine, Fuzhou Second Hospital, Xiamen University, Xiamen, China