Over an 11-month period (November 1992 to October 1993), 32 radiofrequency catheter ablations were performed for recurrent symptomatic supraventricular tachycardia in 17 patients with atrioventricular (AV) nodal reentry, 13 with AV reentry with an accessory pathway), and 2 with both AV and AV nodal reentry. Each patient underwent both diagnostic and therapeutic electrophysiologic study with radiofrequency catheter ablation in a single session. Twelve of the 32 patients had recurrent symptoms after catheter ablation. A repeat study was performed in 9 of the 12 patients. At 7.7 +/- 0.8 months (range 4 to 11) of follow-up only one patient had had a true symptomatic recurrence. Additional sessions of ablation cured this patient. We conclude that pseudorecurrence of paroxysmal supraventricular tachycardia is a common phenomenon in patients after radiofrequency catheter ablation. Follow-up electrophysiologic study demonstrates and helps differentiate pseudo from true paroxysmal supraventricular tachycardia recurrence.