The introduction of angiotensin-converting enzyme (ACE) inhibitors for the treatment of hypertension and heart failure is probably the most important advance in cardiovascular pharmacotherapy in the last few decades. Although the role of the renin-angiotensin system (RAS) in cardiovascular diseases had been investigated extensively for more than 70 yr, the therapeutic application of this knowledge became possible only after the introduction of a practical way to block this system. It is now well established that activation of the RAS has a detrimental effect on the cardiovascular system and promotes arterial, myocardial, and renal damage. ACE inhibition was shown to diminish morbidity and mortality in patients with ischemic cardiomyopathy after myocardial infarction (MI), in patients with left ventricular impairment ranging from subclinical diastolic dysfunction to advanced systolic dysfunction with decompensated congestive heart failure (CHF), and in patients with diabetic nephropathy. Accordingly, these conditions are now compelling indications for treatment with ACE inhibitors (1), even in non-hypertensive patients.