Background: It is evident that prolonged atrial fibrillation is associated with atrial electrical and structural remodeling. We hypothesized that typical atrial flutter (AFL) may induce electrical and structural remodeling in the right atrium. We evaluated the right atrial voltages in patients with AFL. Methods: We enrolled fourteen patients who underwent radiofrequency catheter ablation guided by electroanatomical mapping for AFL. We mapped the entire right atrium (RA) and obtained the bipolar voltages during the AFL. The measured data were compared with those of a normal control (9 patients who had supraventricular tachycardia) and postoperative atrial flutter patients (4 patients), who underwent electroanatomical mapping of the right atrium. A low voltage was defined as less than 1.0mV. Results: The percentages of the low voltages in the entire RA were 24.8% in control, 43.7% in the AFL patients and 62.1% in the postoperative group. The bipolar voltages in the AFL and postoperative groups were significantly lower than that in the control group. The right atrial volume in the AFL and postoperative groups, calculated by electroanatomical mapping was significantly larger than normal. Detailed results are presented in the table. Conclusion: A reduction in the voltage and enlargement of the chamber suggest electrical and structural remodeling of the right atrium by AFL.