Ellenbogen KA, Arrowood JA, Cohen MD, Szentpetery S. McGuire VA Med Ctr, Richmond. J Heart Transplant 1987;6(3):167-70. Esophageal electrocardiography is a commonly used tool for the differential diagnosis of arrhythmias. A 39-year-old man who underwent orthotopic heart transplantation developed a narrow complex tachycardia. Esophageal electrocardiography showed a junctional tachycardia (recording native atrial activity alone), whereas atrial intracavitary electrograms showed the correct diagnosis of atrial flutter. Esophageal recording in patients who undergo orthotopic heart transplantation is a useful technique for recording native atrial activity. For arrhythmia diagnosis in these patients it is frequently necessary to record donor atrial activity with intracavitary electrograms. The limitations of esophageal electrocardiography should be recognized by physicians who care for these patients.