Serum biochemical tests play an important role in the diagnosis and management of acute and chronic liver disease. Their routine use has led to the increased detection of liver enzyme abnormalities in otherwise asymptomatic patients. These tests consist of markers of hepatocellular injury, tests of liver metabolism, and tests of liver synthetic function. Liver injury can be characterized as primarily hepatocellular versus cholestatic based on the degree of elevation of aminotransferases compared with alkaline phosphatase. A comprehensive history, physical examination, and assessment of pattern of liver injury with additional directed laboratory testing establish the cause of hepatobiliary disease in most cases.