Urea transporters (UT) in renal tubule epithelial cells (UT-A) and vasa recta endothelial cells (UT-B) play an important role in the urine concentrating mechanism. Therefore, UTs are regarded as a potential target for diuretics, or ‘urearetics’, with unique mechanisms of action and clinical indications. UT inhibitors have a diuretic effect without causing disorders of electrolyte balance like classical diuretics that induce diuresis by natriuresis. This chapter delves into the screening and evaluation methods used for discovering UT inhibitors, the small molecule UT inhibitors that have been identified to date, and UT inhibitors’ therapeutic effect in hyponatremic animal models. The studies on UT inhibitors as diuretics show promise for treating dilutional hyponatremia associated with conditions like congestive heart failure, cirrhosis, ascites, and nephrotic syndrome, as well as the syndrome of inappropriate antidiuretic hormone (SIADH) secretion.