We report a case of sinus node reentry, an uncommon form of supraventricular tachycardia in a patient with no organic heart disease. This tachycardia appeared at times with wide QRS complexes, which made the differentiation between supraventricular and ventricular tachycardia somewhat difficult. The purpose of this report is to discuss features of sinoatrial node reentry tachycardia, both on surface electrocardiography and intracardiac electrography. Electrophysiologic studies are usually required to confirm the diagnosis.