Penetrating aortic ulceration is uncommon in the infrarenal aorta. We describe a patient with a penetrating infrarenal aortic ulcer manifesting as blue toe syndrome, and a second patient with a similar lesion identified as an incidental finding. These two patients were treated for penetrating infrarenal aortic ulceration within the past 9 months at two university-affiliated hospitals, a regional Veterans Administration Medical Center, and a County Medical Center. Both lesions demonstrated aneurysm changes with varying degrees of mural thrombus. The lesion filled with fresh thrombus proved labile, with embolization manifesting as blue toe syndrome. We support the aggressive treatment of aneurysmal penetrating aortic ulcer with aortic graft replacement to eliminate the potential for distal embolization and to obviate the risk of rupture and death.