The organic anion transporters Oat1, Oat3 and Oat5 belong to the SLC22 family and are mainly located in the kidneys. These transporters interact with endogenous metabolic end products as well as with a several widely used drugs as antibiotic, antivirals, anti-inflammatory drugs and diuretics. Consequently they play an important role in renal drug elimination and have an important influence on pharmacokinetics. In this review we focus on the use of animal experimental models to evaluate the physiological role of these transporters and their expression in the presence of different pathological states. We report studies performed using Oat1 and Oat3 knockout mice which allow the evaluation of their physiological role. The renal expression of Oat1, Oat3 and Oat5 in the presence of pathologies as chronic renal failure, ischemic renal failure, obstructive nephropathy, extrahepatic cholestasis and arterial calcinosis are also reported.