Although angiography is the accepted "gold standard" for demonstrating the presence of arterial occlusive disease, it is less accurate for grading the associated hemodynamic consequences and is prohibitively invasive and expensive to be used as a first-line investigation. Currently available noninvasive tests allow not only for the detection of perfusion abnormalities, but for an appreciation of their severity as well as their likely location. This information is invaluable for predicting the need for revascularization, guiding the choice of reconstructive procedure, and predicting the likelihood of healing of amputation wounds and ischemic lesions. Although some obstructive lesions are easily detected, others require more in-depth testing to reveal and quantify. Consequently, a thorough understanding of available noninvasive diagnostic modalities, including both their capabilities as well as their pitfalls, is paramount to the effective practice of vascular surgery.