Aortic thrombosis rarely occurs without severe atherosclerosis, aneurysm, or cardiosurgical or traumatic state. Arterial thrombosis is commonly related to an inherited and/or acquired hypercoagulable state. A 50-year-old woman presented with diffuse abdominal pain. One day after her admission, she experienced bloody stools. Computed tomography showed multiple extensive thromboses in the aorta and superior mesentery arteries. She underwent a partial jejunoileostomy and colectomy for extensive bowel infarction. Following surgery, her condition deteriorated and she died on the fourth hospital day. At autopsy, gross examination showed 2 large thrombi (7 and 8 cm in length) in the proximal and descending (thoracic) aorta, with mild atherosclerosis. A mesenteric artery thromboembolus with extensive bowel infarction was present. Postmortem laboratory studies revealed an elevated anticardiolipin immunoglobulin G antibody level. The thrombotic state in this patient was considered multifactorial secondary to acquired risk factors, including obesity, mild aortic atherosclerosis with coronary artery disease, and presence of a high titer anticardiolipin antibody.