The renin-angiotensin system and angiotensin converting enzyme (ACE) are increasingly being implicated in the pathogenesis of coronary artery disease and its sequelae. Genetic studies of ACE gene polymorphism hint at an association between the ACE genotype and atherosclerosis. Animal studies have demonstrated the potential beneficial effects of ACE inhibition at a variety of sites, including improvement of endothelial function, inhibition of platelet aggregation, reduction of atherosclerosis, and inhibition of myointimal proliferation. Although these have not all been validated in human studies, the reduction of ischemic events in studies of ACE inhibition in left ventricular dysfunction cannot be explained solely by improved hemodynamics, and it is possible that actions on the endothelium, the atherosclerotic process, and platelets are at least in part responsible. The results of studies in humans looking more directly at the influence of ACE inhibitors on atherosclerosis and ischemic heart disease are awaited.