['Isolation of the pulmonary veins alone (PVI) is associated with a 50 to 70 % success rate in paroxysmal atrial fibrillation (AF) but is significantly lower for persistent AF. We sought to evaluate patient outcomes in terms of safety and efficacy when posterior left atrial box isolation is included as a catheter ablation strategy in patients with mainly persistent AF.', 'We performed an audit of 100 patients undergoing left atrial (LA) box isolation. Recurrence of arrhythmia was detected by evaluating symptoms and continuous 24 h ECG monitoring at 2, 6 and 12 months post procedure.', 'Seventy-two patients had persistent AF prior to procedure. Average duration of AF was 5.4 ± 5.2 years. All patients underwent circumferential PVI plus linear posterior LA lines to complete box isolation. At a mean follow-up of 12.5 ± 4.2 months, 75 patients were free from atrial fibrillation, 50.6 % of these were taking no antiarrhythmic medication. Twenty-five patients had recurrence of AF, 84 % of whom had previous persistent AF. The average time to recurrence post procedure was 5.9 ± 4.4 months. Thirteen patients underwent repeat procedures for recurrent AF. There were no adverse events relating to the procedure.'] Is clinical outcome when left atrial posterior wall box isolation included as a catheter ablation strategy in patients with persistent atrial fibrillation?