We report two cases of acute aortic thrombosis in cancer patients. Aortic thrombosis is rare in the absence of atherosclerosis, dissection, or aneurysm. On the one hand, hypercoagulable state related to cancer is a well-known risk factor for venous thrombosis. On the other hand, arterial thrombosis has been rarely reported in cancer patients. Recognition of aortic thrombosis is important because it is a dangerous condition; furthermore, it exposes at the patient to complications such as peripheral embolism. In addition, anticoagulation can result in resolution of thrombosis.