Recent insights into the cellular and molecular mechanisms that control the function and regulation of hepatobiliary transport have led to a greater understanding of the physiological significance of bile secretion. Individual carriers for bile acids and other organic anions in both liver and intestine have now been cloned from several species. In addition, complex networks of signals that regulate key enzymes and membrane transporters located in cells that participate in the metabolism or transport of biliary constituents are being unraveled. This knowledge has major implications for the pathogenesis of cholestatic liver diseases. Here, we review recent information on molecular aspects of hepatobiliary secretory function and its regulation in cholestasis. Potential implications of this knowledge for the design of new therapies of cholestatic disorders are also discussed.