This chapter discusses the diagnosis, evaluation and management of abdominal aortic aneurysms (AAA). The classic triad of ruptured AAA is hypotension, pain, and pulsatile abdominal mass. This occurs in only half of the patients. Typical pain is usually described as abdominal or lower back. Any patient with these symptoms and a known AAA is at risk for imminent rupture, if rupture has not already occurred. Vital sign stability should not be reassuring as these patients can deteriorate rapidly. Hypotension is the least consistent part of the triad, occurring in as few as one third of patients. Inflammatory aneurysms may present with fever or weight loss. Patients may complain of pain in the chest, thigh, inguinal area, or scrotum. Initial blood loss may be minor and the patient may present with normal vital signs. Vital sign stability should not necessarily be reassuring as these patients can deteriorate rapidly.