During 1993 the indications for the use of angiotensin-converting enzyme (ACE) inhibitors were expanded to include patients with left ventricular dysfunction and acute myocardial infarction. The role and use of ACE inhibitors in patients with chronic systolic ventricular dysfunction, established in earlier trials, has been further clarified. Increasing attention is being focused on ACE inhibitors, specifically the mechanisms by which they improve mortality, their side effects, and the possibility of further increasing their use by avoiding renal dysfunction and first-dose hypotension. Although most of the interest has centered on ACE inhibitors, the importance of diuretics and their use in combination with ACE inhibitors is being clarified. Most important has been the demonstration over the past year of the effectiveness of digoxin in preventing cardiac deterioration in patients with systolic left ventricular dysfunction and sinus rhythm. The increased understanding of the renin-angiotensin-aldosterone system, its modification by ACE inhibitors, and the interaction of ACE inhibition with other drugs provides the basis for a further improvement in morbidity and mortality in patients with heart failure.