WPW syndrome is a rare congenital heart disease due to an accessory pathway between the atrium and the ventricle. Its ECG pattern is characterized by a short PR interval, a delta wave, a wide QRS complex and an abnormal ventricular repolarisation. Patients are usually asymptomatic, or have frequent paroxysmal episodes of tachycardia. These tachycardias are supraventricular tachycardias related to either reentry between the AV node and the accessory pathway, or atrial tachyarythmias descending through this bypass tract, or both. In the latter clinical situation, sudden cardiac death may occur in case of short refractory period within the accessory pathway. An electrophysiologic study should be performed in order to characterize and localize this accessory pathway. If this pathway is capable of conducting rapidly anterogradely, we recommend an immediate radiofrequency ablation in both symptomatic and asymptomatic patients. In the contrary, medical or ablation therapy are indicated only in symptomatic patients.