Department of Medicine, Brigham and Women"s Hospital, Boston, Massachusetts 02115, USA. The Prevention of Events with Angiotensin-Converting Enzyme Inhibition (PEACE) trial is an 8,100 patient, randomized, double-blind, placebo-controlled trial designed to determine the usefulness of angiotensin-converting enzyme (ACE) inhibitors in treating coronary patients with preserved left ventricular ejection fraction. The hypothesis being tested in this trial is that patients with coronary disease and ejection fraction > or =40% who are treated with ACE inhibitors will experience a reduction in the incidence of cardiovascular death, nonfatal myocardial infarction, or a revascularization procedure compared with patients treated with conventional therapy. The design of the PEACE trial is described herein.