Introduction: A 34 year old female with a 10 year history of incidentally diagnosed premature ventricular beats (PVBs), complaining of brief palpitations, was referred to our EP Department. She denied any history of syncope, lipotimia or sudden cardiac death in her relatives. All the antiarrhythmic drugs failed to control/ reduce the PVBs number. Methods: ECG showed NSR, RBBB-like inferior axis PVBs with high burden on the 24 h Holter monitoring and alternating T wave morphology in V1-V4 (i.e negative vs positive) rising the suspicion of arrhythmogenic right ventricular dysplasia (ARVD).Transthoracic echocardiography was normal. On treadmill exercise test, the PVBs disappeared with the increase in exercise load and SR rate, recurring as ventricular bigeminism in recovery. Cardiac MRI described a RVOT small dyskinetic area, below the pulmonary valve. EPS study and successful RFCA were performed using a 3D electroanatomic mapping system. Results: Voltage mapping showed an area of scar confined to the one described by MRI. The bipolar endocardial area perfectly matched the epicardial unipolar one, unusual in ARVD, in whom the epicardial scar is much more extensive than the endocardial one. At long term follow-up she was completely asymptomathic, without evidence of PVBs recurrence. Conclusions: In conclusion, 3D electroanatomic voltage mapping is useful in elucidating the etiology in the challenging cases, where other imaging technologies fail in clarifying it.