This article reviews the distinguishing features of epidemiology and clinical medicine and their interdependence in clinical epidemiology as applied to vascular disease. Selected literature is reviewed to emphasize the principles of clinical epidemiology for five vascular disorders: abdominal aortic aneurysms, lower extremity peripheral arterial occlusive disease, cerebrovascular disease, deep vein thrombosis and pulmonary embolism, and varicose veins. These vascular disorders are prevalent and pose significant risks for death and disability. Many have risk factors that can be controlled. All can be treated by vascular surgery, but outcomes including functional health and well-being may fall short of that which is implied in our traditional surgical literature. Appropriate allocation of resources to detect and treat vascular disease demands that clinicians not only assume responsibility for the care of individual patients but also develop a working knowledge of the clinical epidemiology of vascular health and disease and its management within populations.