The clinical effects of early intravenous beta-blockade followed by short-term oral treatment in acute myocardial infarction (MI) have been studied in 30 randomized trials totaling almost 28,000 patients. This treatment reduces the incidence of infarction by 10-15% in patients with threatened MI, reduces infarct size by 20-30%; reduces the incidence of nonfatal reinfarction, nonfatal cardiac arrest and mortality each by about 15%. Treatment has to start within 12 h of the onset of symptoms to be able to reduce measures of infarct size and infarct development. If patients are carefully selected serious side effects are rare and reversible. Based on the different presumed mechanisms of benefit it would be reasonable to expect the combination of i.v. beta-blockade and other therapies of proven benefit to be more beneficial than either class of agent used alone.