Bile acids and their salts have essential functions in the liver and small intestine. Synthesis of bile acids in the liver provides a major catabolic pathway for cholesterol. In the intestine, bile salts aid in the emulsification of lipids and solubilization of essential nutrients and vitamins. The secretion of bile normally depends on the function of membrane transporters in the hepatocytes and cholangiocytes. The coordinated action of these transporters is crucial to hepatic drug clearance, biliary secretion of cholephilic compounds and xenobiotics. Manydrugs and their metabolites inhibit the hepatobiliary transport system. In addition to direct drug inhibition, the function of these transporters can be compromised by metabolic, autoimmune, infectious or genetic disorders. The impairment of bile flow in the liver is called hepatic cholestasis, which is clinically characterized by elevated plasma concentrations of cytotoxic biliary constituents, malabsorption of fats and liver damage.