Exercise-induced ventricular tachycardia (VT) is rare in children and young adults without structural heart disease. Catecholaminergic polymorphic VT (CPVT) is among the possible causes and carries a poor prognosis. The QRS morphology of CPVT can be bidirectional, polymorphic or even ventricular fibrillation. We report a case of CPVT initially presenting as sudden collapse in an 18-year-old Taiwanese woman. Family history was negative for arrhythmias and sudden death. Laboratory analyses, transthoracic echocardiography, magnetic resonance imaging, electrophysiological study including procainamide and isoproterenol test were all negative. Bidirectional VT was induced by treadmill exercise test. She responded well to beta-blocker therapy. Some cases of CPVT are sporadic and some occur in patients with a family history. The treatment of choice for this disease is beta-blocker and implantation of an internal cardioverter defibrillator.