Atrial ectopic tachycardia is an incessant supraventricular tachycardia and is frequently refractory to medical treatment. Because it can cause tachycardia-induced cardiomyopathy, early diagnosis and treatment is important. We present a 16-year-old boy who was diagnosed as atrial ectopic tachycardia. The tachycardia, originating from the lower region of the right atrium along the crista terminalis was terminated by successful radiofrequency ablation treatment. The tachycardia did not recur in eight months of follow-up.