ABSTRACT. Electrophysiologic procedures, including radiofrequency ablation of cavotricuspid isthmus (CTI)-dependent atrial flutter, typically require varying amounts of fluoroscopy, which could be completely eliminated with electroanatomic mapping. We compared 20 consecutive patients who underwent fluoroless ablation for atrial flutter (Group A) with a prior series of 20 patients with standard flutter ablation (Group B). CARTO 3 mapping software was used to position diagnostic and ablation catheters in Group A; the ablation catheter was used to create a shell of the right atrium and coronary sinus (CS), and to guide CS catheter positioning. Atrial flutter was ablated successfully and bidirectional CTI block achieved without complication in all patients in both groups. Mean fluoroscopic duration and dose in Group B was 6.3 ± 3.3 min and 138±119 mGy respectively. There was no difference between Group A and Group B in procedure duration (110.2 ± 43.1 versus 114.9 ± 29.2 minutes, p ¼ 0.69), ablation duration (15.0 ± 11.7 versus 17.2 ± 10.1 min, p ¼ 0.52), time to ablation start (40.4 ± 13.3 versus 41.9 ± 14.8 min, p ¼ 0.74), and time from CS catheter insertion to optimal placement (5.4±4.4 versus 6.3±5.0 minutes, p ¼ 0.74). There was also no significant difference in these parameters between the first and last 10 patients in Group A. Fluoroless ablation for right atrial CTI-dependent flutter is safe and practical, with obvious advantages of avoidance of radiation exposure to patients and staff. Further studies are warranted applying these principles to other arrhythmia substrates.