A patient, 59 years old male, with paroxysmal AV reentrant tachycardia utilizing a concealed left lateral accessory pathway with long VA conduction time is presented. During tachycardia P waves were negative in leads I, aVL, and V6 and positive in leads aVR and V1. The R-P/P-R ratio was 1.6. Radiofrequency catheter ablation was successful to interrupt the VA conduction through the accessory pathway.