The authors describe a patient who experienced recurrent wide-complex and narrow-complex tachycardias during exercise. Electrophysiologic testing in the resting state revealed dual atrioventricular (AV) nodal pathways. AV nodal reentrant tachycardia was inducible by ventricular premature stimulation but was always nonsustained, terminating with block in the anterograde slow pathway. During isoproterenol infusion, runs of ventricular tachycardia occurred frequently, and spontaneously initiated sustained AV nodal reentrant tachycardia. Exercise testing also provoked ventricular tachycardia and sustained AV nodal reentrant tachycardia. The patient was effectively treated with a combination of atenolol and verapamil. This case is an unusual example of a catecholamine-induced arrhythmia, possibly due to triggered activity (exercise-induced ventricular tachycardia), initiating an arrhythmia due to reentry (AV nodal reentrant tachycardia).