Catheter ablation of ectopic atrial tachycardia has been previously reported in a small number of patients in whom the ectopic focus was predominantly located in the right atrium. We report on a 53-year-old patient with atrial automatic tachycardia originating in the left atrium, in whom successful radiofrequency catheter ablation was performed via a transseptal puncture. The patient presented a permanent atrial tachycardia for several years, refractory to antiarrhythmic drug treatment and DC-cardioversion. Radiofrequency ablation terminated left ectopic atrial tachycardia and, therefore, should be attempted before resorting to open-heart surgical ablation.