Since the introduction of angiotensin converting enzyme (ACE) inhibitors into clinical use, much information has been accumulated in animal models and man regarding their effects on renal function in different disease states. Enalapril, the first nonsulfhydryl ACE inhibitor approved for general use in the United States, has demonstrated efficacy and safety in controlling blood pressure in patients with essential hypertension, renal parenchymal disease, renovascular hypertension, and diabetes with hypertension. Enalapril also appears capable of attenuating the progressive nature of renal disease in experimental models of chronic renal failure and diabetic nephropathy, perhaps through lowering intraglomerular pressures. The excellent blood pressure-lowering effects of ACE inhibitors, coupled with their potential to ameliorate renal hemodynamic abnormalities, make these compounds attractive for use in these clinical states.