The organic anion transporting proteins (OATPs) belong to the SLC gene superfamily of transporters and are 12 trans-membrane domain glycoproteins expressed in various epithelial cells. Some OATPs are expressed in a single organ, while others occur ubiquitously. The functionally characterized members of the OATPs mediate sodium-independent transport of a variety of structurally independent, mainly amphipathic organic compounds, including bile salts, hormones and their conjugates, toxins, and various drugs. Uptake transporters (OATPs, NTCP, OCT1, and OAT2) are localized in the basolateral membrane. These transporters mediate the uptake of substrates into the liver from the circulation. OATP1B1 and OATP1B3 are liver specific and show broad substrate specificity (statins, rifampicin, and telmisartan). Inhibition of OATP-mediated uptake of several statins by cyclosporin A and rifampicin causes clinically significant DDIs