Aortic malignant neoplasms are rare; these may be primary or secondary (metastatic). Increasing use of cross-sectional imaging has allowed better detection and diagnosis of these conditions. We encountered a young woman presenting with acute abdomen who was found on cross-sectional imaging to have a malignant tumor involving the aortic bifurcation. An en bloc excision of the tumor was performed, with distal aorta reconstruction using an aortoiliac Dacron graft; this was complicated with infection and graft occlusion, necessitating total removal and extra-anatomic bypass. A pathologic diagnosis of metastatic adenocarcinoma involving the aortic bifurcation, with an unknown primary, was made.