Important ongoing experimental and clinical research is evaluating the potential use of ACE inhibitors in a wider range of patients, in addition to their well accepted use in heart failure, left ventricular dysfunction and hypertension. We review briefly the clinical data supporting a potential role for ACE inhibitors in the prevention of myocardial infarction and stroke and the wider use of these agents in hypertension, renal disease and diabetes. We also briefly review the major ongoing trials evaluating these hypotheses.