Propafenone is a potent antiarrhythmic agent effective in either supraventricular or ventricular tachyarrhythmias. For proper utilisation, some important pharmacological aspects must be considered, such as nonlinear pharmacokinetics, inability in some patients (poor debrisoquine metabolisers) to oxidise the drug in the liver, existence of at least one active metabolite (5-hydroxy-propafenone) and ability to exert a slight beta-blocking activity. Like all the other antiarrhythmic drugs, propafenone may be associated with adverse effects and may exert proarrhythmic effects. For this reason, its usage must be based on a careful analysis of the risk-benefit ratio, by considering the patient's profile as well as the characteristics of the arrhythmia and its prognostic significance. Propafenone appears to be very effective, and has a favourable risk-benefit profile in the treatment of all supra-ventricular arrhythmias. Particularly, it is effective in converting atrial fibrillation to sinus rhythm and in preventing atrial fibrillation recurrences, and is very effective in the pharmacological control of the arrhythmias of the Wolff-Parkinson-White syndrome. Propafenone is also effective in suppressing ventricular premature complexes and nonsustained ventricular tachycardias. However, because of potential proarrhythmic effects, its use in these arrhythmias must be considered after a careful analysis of the risk-benefit profile, which could be favourable in some patients, but less favourable in others (e.g. patients with coronary artery disease and ventricular dysfunction). In malignant ventricular arrhythmias, further studies are needed to define the limitations of antiarrhythmic drugs in comparison with non-pharmacological treatments, mainly cardioverter/defibrillators. At present, like the other class I antiarrhythmic agents, propafenone does not seem to be a first choice prophylactic agent for malignant ventricular arrhythmias, although more data from controlled studies are needed.