In recent years, several large randomized trials have clarified the role of various interventions in acute myocardial infarction. There is clear evidence that thrombolytic therapy, aspirin, and beta-blockers reduce mortality. Both aspirin and beta-blockers also reduce reinfarction and stroke. Of the thrombolytic agents, comparative trials have established that tissue plasminogen activator and streptokinase have similar effects on mortality, morbidity, and left ventricular function. There appears to be an increased risk of cerebral hemorrhage with tissue plasminogen activator. The benefits of heparin in conjunction with aspirin and a thrombolytic agent are unclear and, at best, are likely to be modest. Heparin increases the risk of hemorrhagic complications twofold. Although trials of vasodilators conducted before the widespread use of thrombolytic therapy and aspirin have been promising, newer trials are needed to evaluate their effects among patients receiving these agents. The aggregate of all trials of the routine use of calcium antagonists or antiarrhythmic agents indicates that these agents do not improve survival.