We report an observation of a radiofrequency catheter ablation of an accessory pathway (AP) in a patient with Wolff-Parkinson-White syndrome (WPW) and dextroversion. Atrioventricular rings were mapped by the ablation catheter to locate the shortest local atrioventricular conduction time in sinus rhythm and ventriculoatrial conduction time during orthodromic tachycardia or ventricular pacing. Successful ablation confirmed a right posteroseptal AP localization. Thus, the electrocardiographic modifications due to an AP in this location in the presence of dextroversion were defined.