An interesting case of congenital intrapericardial aneurysm of the left-atrial appendage is reported. The patient presented with recurrent supraventricular arrhythmias and progressive exercise intolerance and fatigue. Computerised axial tomography aided in the diagnosis by excluding the presence of any thrombus in the sac. The aneurysm could be safely excised via a left thoracotomy without cardiopulmonary bypass. The relevant literature on this problem is briefly discussed.