Recent trials have shown that angiotensin-converting enzyme (ACE) inhibitors can reduce mortality and the occurrence of severe left ventricular dysfunction (LVD) when started within the first day after acute myocardial infarction and continued for 4-6 weeks thereafter. When started within this time window, ACE inhibitors are safe in relatively unselected myocardial infarction (MI) patients provided they are clinically and hemodynamically stable. GISSI-3, ISIS-4 and CCS-1 studies show that more than half of the lives are saved by ACE inhibitor treatment within the first week of therapy. Although the benefit from ACE inhibitors is larger in patients presenting with congestive heart failure (Killip class > 1), the number of lives saved in patients at low risk, who represent the majority of the population, is relevant. This supports the approach of treating all hemodynamically stable MI patients. Treatment could be stopped after about 1 month in patients without evidence of LVD while those with LVD should follow a long-term therapy with ACE inhibitors.