Four of 12 patients (33%) with paroxysmal supraventricular tachycardia (PSVT) and tachycardia-induced atrial fibrillation (AF) had recurrences of paroxysmal AF after successful catheter ablation of the PSVT. This study demonstrates that AF often remains a problem after radiofrequency catheter ablation of PSVT in patients with tachycardia-induced AF, and it may not be possible to predict in which patients this will be the case.