Background: Box isolation of the posterior left atrium is one surgical or catheter ablative approach for treating atrial fibrillation (AF). In such cases, incomplete transmurality or recovery of pulmonary vein conduction after the application of various ablative techniques is considered the main reason for the recurrence of postprocedural arrhythmia. The use of solely cut-and-sew box isolation does not have these disadvantages and therefore demonstrates maximum efficacy for this therapeutic approach. Methods: We treated 15 patients with both an indication for open heart surgery and AF (2 paroxysmal, 6 short persistent [<12 months], and 7 long persistent [>12 months] cases) with a solely cut-and-sew box lesion. These patients were then retrospectively followed up over the long term with respect to the end point of freedom of atrial tachyarrhythmias >30 seconds. Results: The median follow-up duration was 42 months (range, 32-84 months). Five (63%) of 8 patients with preoperative paroxysmal or short persistent AF had no arrhythmia recurrence, whereas arrhythmia recurrence was documented in all 7 patients with preoperative long persistent AF. Conclusions: Despite reliable transmural isolation with cut-and-sew lesions, we observed long-term arrhythmia recurrence in patients who had preoperative paroxysmal or short persistent AF, suggesting that therapy approaches that are more complex than box isolation might be needed for selected patients to achieve long-term stable sinus rhythm, despite the initially paroxysmal or short persistent character of the arrhythmia. A high rate of recurrence in patients with severe structural heart disease and preoperative long persistent AF might indicate that, in general, isolation of the left posterior atrium alone is not an adequate therapeutic approach for these patients.