Atherosclerosis is a systemic disease that afflicts millions of patients annually in the United States. Historically, most of the clinical focus has been on its coronary artery manifestations, given their frequency and the potentially grave consequences. While vascular medicine and vascular surgical specialists, however, have long recognized that peripheral (extracardiac) arterial occlusive disease may contribute significantly to morbidity and mortality, it is only recently that invasive and interventional cardiologists have become involved in its diagnosis and management. To support that involvement, the scope of this chapter has been extended beyond the usual aortic diseases (such as dissection) to include information on atherosclerosis as it affects other major arterial territories. It reviews the natural history, clinical presentation, noninvasive diagnostic modalities, and angiographic techniques that are of value in patients with peripheral vascular disease, including aneurysmal disease of the thoracic and abdominal aorta, and atherosclerotic disease of the extracranial carotid arteries, renal arteries, and lower-extremity arteries. Additional information regarding interventional techniques is reviewed in Chapter 27, and representative case profiles are reviewed in Chapter 35.