Recent results obtained from large clinical trials demonstrate that long-term administration of beta-adrenergic antagonists to patients following myocardial infarction reduces the incidence of death for as long as two years. Therefore, it has been recommended that, in the absence of contraindications, all patients be given beta antagonists after infarction. A review of the literature regarding prognosis after infarction demonstrates that patients who have had only one infarction and who have good ventricular function, no complex ectopy, no angina, and negative results of stress testing have a mortality rate no greater than 0.6 percent per year. For a person in this category, the probability that beta blockade will preclude death is exceedingly low (approximately 1 in 700). Both the commonly described side effects, as well as the recent observation that beta-adrenergic antagonists lower the concentration of serum high-density lipoproteins, potentially reducing the protection against atherosclerosis thought to be conferred by high-density lipoproteins, suggest that it may be unwise to use beta antagonists in patients who have a very low probability of benefit.