A nine-year-old girl had an episode of atrial flutter and a nonsustained wide QRS tachycardia during her initial hospitalization after orthotopic heart transplantation. Evaluation of her ECG and telemetric tracing revealed atrial flutter of the recipient atrium and sinus rhythm of the donor atrium. The wide QRS tachycardia was an accelerated ventricular rhythm that was also found on subsequent 24-hour ambulatory ECG monitoring. Timely recognition of recipient atrial arrhythmias prevents inappropriate clinical intervention.