Sotalol hydrochloride (Betapace), recently released by the Food and Drug Administration for general use, is used to treat a variety of ventricular and supraventricular tachyarrhythmias. The drug's dominant action is the result of combined nonselective beta-adrenergic antagonism (Class II effect) and monophasic action potential duration prolongation in all cardiac tissues (Class III effect). It causes less left ventricular depression than propranolol and has a low incidence of toxicity. It is a useful addition to the antiarrhythmic drug armamentarium. This article reviews the drug's pharmacokinetic, pharmacodynamic and electrophysiologic properties, clinical uses and potential side effects. Reports on the drug's use as an antianginal and antihypertensive agent are also discussed.