Radiofrequency (RF) ablation of the isthmus between the inferior vena cava and the tricuspid ring has proven to be a safe and successful method of treating atrial flutter (AF). However, RF ablation lesions are small in size requiring a considerable number of energy applications to ablate the AF circuit. The aim of this study was to evaluate the feasibility and efficacy of microwave energy for AF ablation. We report a case of sustained typical AF treated successfully and safely by 1 pulse of microwave (MW) energy. This showed it is possible to treat AF with a small number of pulse applications.