Continuous enlargement of the aneurysmal sac after endovascular stent-graft treatment of thoracic aortic aneurysms due to graft wall porosities (type V endoleak) is a novel problem. Two patients having undergone prior endovascular stent-graft placement of a thoracic aortic aneurysm presented with a continuous enlargement of the aneurysmal sac without a detectable endoleak. Both patients underwent redo stent-graft placement. Subsequently, shrinkage of the aneurysmal sac could be observed. Therefore endovascular redo stent-graft placement may represent an effective means in treating type V endoleaks.