The right atrial appendage atrial tachycardia (RAA AT) has been previously reported as a rare site in focal AT. We report a patient with a history of a right pneumonectomy who underwent catheter ablation of the AT originating from the RAA. This RAA AT showed unusual P-wave morphology compared with previous reports. We describe the RAA AT following right pneumonectomy using a NavX system (St. Jude Medical, St. Paul, MN, USA).