Noninvasive diagnostic techniques have become a recognized adjunct in screening and follow-up of patients with peripheral arterial, venous, and cerebrovascular diseases. These techniques provide physiologic information at little or no risk to patients. Although primarily of diagnostic intent, these studies are also expanding our knowledge base about the natural history of peripheral vascular diseases and the efficacy of various interventions. Advances in radiology have complemented but not replaced the need for the noninvasive peripheral vascular laboratory. It is incumbent upon all physicians to appreciate the diagnostic value and recognize the limitations of these noninvasive techniques. Intelligent use of these modalities may enhance patient care without significantly increasing health care costs. Further prospective studies of the cost benefit or effectiveness of these techniques are indicated.