We detail the simultaneous surgical treatment of Ebstein's anomaly combined with Wolff-Parkinson-White syndrome in a patient who presented with multiple accessory conduction pathways. The extensively deformed tricuspid valve was replaced by a Hancock xenograft and the atrialized ventricle was plicated. Surgery was performed under the beating heart condition and this made possible electrical mapping which facilitated the localization of both accessory pathways. By the method presented here, all existing accessory pathways can be pinpointed during open heart surgery and the time of their interruption can be established. Two and a half years after surgery, chest X-ray revealed marked reduction of the cardiothoracic ratio and the patient experienced no postoperative tachycardia episodes.