A 16-year-old boy suddenly fell off his stool, a 26-year-old man had persistent palpitations and a 29-year-old man was reanimated without an incriminating anamnesis. The diagnosis 'Wolff-Parkinson-White(WPW)-syndrome' was made in all three cases. The boy died as a result of postanoxic neurological injury; in the two men, further cardiac rhythm disturbances were prevented by interrupting the accessory atrioventricular connection via radiofrequency catheter ablation. In ECG databases, a WPW-pattern is encountered in 1-3 of 1000 electrocardiograms. Atrial fibrillation with 1:1 conduction via the accessory pathway, leading to ventricular fibrillation, is the most common cause of sudden death in WPW-patients. In some cases, atrial fibrillation with a rapid ventricular response is the first sign of the syndrome. The risk of sudden death in these patients is estimated to be 0.0-0.6% per patient per year and cannot be predicted easily. Curative treatment is possible in the form of radiofrequency catheter ablation.