Objectives: This study describes the electrophysiologic and electrocardiographic characteristics of focal atrial tachycardia (AT) arising from superior tricuspid annulus in six (1.9%) patients of a consecutive series of 320 patients. Methods: Six patients (mean age 42 +/- 22 years) with a mean cycle length of 326 ms of a consecutive series of 320 patients undergoing radiofrequency ablation for focal AT were mapped. Results: During electrophysiologic study, tachycardia could be induced in five patients with programmed atrial extrastimuli while a spontaneous onset and offset with 'warm-up and cool-down' phenomenon was seen in the other patient. During tachycardia, P-wave morphology in Lead I, II, III and aVF was upright in all the six patients. The precordial leads were dominantly negative or isoelectric in V-1-V-2 and positive in V-5-V-6 with a transition at V-3 or V-4. Moreover, the tachycardia was sensitive to intravenous administration of adenosine triphosphate in five of six patients. Conclusions: Radiofrequency ablation was performed successfully in all patients (mean 4.5 +/- 1.2 applications). No recurrence of AT was observed after a mean follow-up of 8 +/- 6 months. Thus, AT arising from superior tricuspid annulus is rare. Radiofrequency ablation of this kind of AT is safe and effective.