This is a case report of a twenty-two-year-old woman who had attacks of ventricular tachycardia that could be prevented by the use of various antiarrhythmic drugs for three months. Electrophysiologic study showed that the mechanism of the tachycardia was "reentry." In cardiac catheterization a non-contractile mass having calcification was seen on the apical portion of the left ventricle. Angiographically, the mass resembled a diverticulum. Recurrence of attacks was terminated by resection of this mass, which had a cystic appearance.