An aortic aneurysm should be diagnosed before it ruptures; nearly all aneurysms can be treated surgically. An aneurysm found incidentally or through screening should be monitored until it reaches a size where the benefit of a surgical repair outweighs the operational risk. The risk of rupture is small in aneurysms < 5 cm in diameter. It is easy for a primary care physician to learn the diagnosis of an abdominal aortic aneurysm with ultrasonography. The possibility of aortic dissection must be considered in a patient with severe pain suggestive of acute myocardial infarction but without clear ECG changes. A patient with a ruptured aneurysm or aortic dissection needs immediate hospitalization.