The liver plays an important role in the detoxification of xenobiotics. Recently, many secondary active transporters responsible for sinusoidal drug uptake have been cloned and their transport properties have been determined. These include rat and human Na(+)-taurocholate cotransporting polypeptides, rat and human organic anion transporting polypeptides, rat and human prostaglandin transporters, rat organic anion transporters, and rat and human organic cation transporters. In addition, it has been suggested that the expression of multi-drug resistance associated protein 3, a primary active transporter responsible for the cellular extrusion of organic anions, on the sinusoidal membrane is induced under cholestatic conditions. In this article, drug transport across the sinusoidal membrane is summarized, particularly focusing on the molecular mechanism of transport.