This review focuses on the use of angiotensin converting enzyme (ACE) inhibitors in hypertensive diseases. Specifically discussed are: proposed mechanisms of action, the pharmacology of the commercially available ACE inhibitors (captopril, enalapril, and lisinopril), their renal effects, and their safety and efficacy. The ACE inhibitors are assuming a dominant role in our therapeutic armamentarium, in that they are well-tolerated and very effective in the treatment of mild, moderate or severe hypertension.