During recent years, it has become increasingly recognized that drug transporters play important roles in drug absorption and disposition. Organic anion transporting polypeptides (OATPs) are membrane transporters critically involved in the cellular uptake of drugs in tissues important for pharmacokinetics, such as the intestine, liver and kidneys. Recent advances in the pharmacogenomics of OATP1B1 have revealed that OATP transporters can play important roles in explaining interindividual variability in drug pharmacokinetics, and thus contribute to interindividual as well as interethnic variability in drug response. This article will provide an up-to-date review of human OATPs and their substrates, and a current compilation of their DNA sequence variations.