The angiotensin-converting enzyme (ACE) inhibitors available today include Captopril (Capoten), enalapril (Vasotec), enaloprilat (Vasotec IV), lisinopril (Prinivil, Zestril), benazepril (Lotensin), fosinopril (Monopril), and ramipril (Atace). These drugs are used in the treatment of hypertension and congestive heart failure. They also are used in treating renovascular hypertension not amenable to surgery and are being studied to decrease left ventricular size after infarction and to determine whether they slow the rate of internal hyperplasia. Angiotensin-converting enzyme inhibitors have negative inotropic and chronotropic effects. This chapter discusses the ACE inhibitors and their actions, uses, adverse effects, contraindications, and nursing implications