By the mid 1960s a beneficial effect of post-myocardial infarction treatment with beta-blockade had been proposed. However, it was not until 1981 that large clinical trials clearly demonstrated a beneficial effect both in terms of reduction in mortality and morbidity. Today treatment with beta-blockers both in the acute phase of acute myocardial infarction as well as in the stable post-myocardial infarction patient is well established. In this review article, different aspects of early and late treatment with beta-adrenoceptor blockers are discussed. The cardioprotective effects of beta-blockers on mortality and morbidity should not be considered class effects valid for all beta-blockers. Pooled data have clearly demonstrated that beta-blockers with intrinsic sympathomimetic activity have less marked effects. Impressive effects on mortality and morbidity have been obtained with propranolol, timolol, and metoprolol, which are noncardioselective as well as more beta 1-selective (metoprolol), but they are all lacking intrinsic sympathomimetic activity and, furthermore, have a relatively high degree of lipophilicity. It is clear that acute beta-adrenoceptor blockade in suspected acute myocardial infarction reduces mortality and morbidity as well as complications such as chest pain and ventricular arrhythmias during the acute phase. In post-myocardial infarction treatment, it is clear that both mortality and morbidity are reduced. Reports from extended follow-ups after termination of initial double-blind beta-blocker studies in postinfarction patients indicate that withdrawal of the active treatment may increase mortality after cessation of treatment. This is observed despite measures having been taken to avoid so-called acute withdrawal phenomena.(ABSTRACT TRUNCATED AT 250 WORDS)