A 14-year-old boy without overt heart disease underwent encircling ventriculotomy and cryoablation because of ventricular tachycardia resistant to antiarrhythmic therapy. Resection of the right ventricular wall with the origin of the ventricular tachycardia was performed on the basis of information obtained by epicardial mapping at operation, and histological examination showed unique findings of remarkable fatty infiltration and lymphocytic myocarditis.