In the thrombolytic era, the mortality of myocardial infarction has been considerably reduced. The prognosis has also improved due to early treatment and the correction of residual ischaemia. Betablockers are valuable antiarrhythmic agents, both in the acute and chronic phases of infarction. Irrespective of the size of the infarct scar, a better prognosis is observed in patients taking betablockers. Class I antiarrhythmics, though, should be proscribed after the results of the CAST studies: these antiarrhythmics are effective on ventricular arrhythmias but do not improve the prognosis because of their proarrhythmic effects aggravated by ischaemia or left ventricular dysfunction. Of the Class III antiarrhythmics, amiodarone has been shown to reduce the incidence of sudden death in the post-infarction period in patients with ventricular hyperexcitability or severe left ventricular dysfunction. At present, classical antiarrhythmic therapy is opposed to the implantation of an automatic defibrillator in cases of serious arrhythmias after myocardial infarction.