Angiotensin-converting enzyme (ACE) inhibitors have been shown to reduce the risk of death, worsening heart failure, and recurrent myocardial infarction in patients with left ventricular systolic dysfunction and heart failure. They have also been shown to reduce mortality in acute myocardial infarction and to reduce the risk of major vascular events and progression of renal disease in patients with diabetes and hypertension, compared with placebo and with calcium channel blockers. Ongoing experimental and clinical research is evaluating the potential use of ACE inhibitors in a wider range of patients, with emphasis on their possible role in the prevention of myocardial infarction, stroke, and cardiovascular death in patients with coronary artery disease without clinical manifestations of heart failure and with preserved left ventricular systolic function, and in high-risk individuals with hypertension, renal disease, and diabetes, in the absence of established ischemic heart disease...