This report describes a case of left atrial appendectomy after a failed endocardial catheter ablation of a continuous drug-refractory left atrial appendage (LAA) tachycardia in a 9-year-old boy. Electrophysiologic study showed atrial tachycardia (AT) originating in the LAA. Numerous radiofrequency applications with an irrigated-tip catheter were ineffective. During surgery, direct pressure on the apex of the LAA by forceps immediately terminated the AT and restored sinus rhythm. After a left atrial appendectomy, the patient remained free of any arrhythmias during a follow-up period of 18 months.