An acute aortic thrombosis in the absence of atherosclerosis, aortic dissection, or aneurysm is an infrequent clinical entity and has been rarely reported in the literature. However, because of serious complications such as an embolism that can be fatal, one should always pay attention to the possibility of its occurrence. We report two cases of an acute aortic thrombosis of lung cancer patients treated with chemotherapy and a review of the literature.