Angiography currently is the principle diagnostic test for evaluation of the vasculature. Though this invasive radiologic procedure demonstrates vascular anatomy and areas of narrowing and blockage, it does not define the specific cause of the occlusion. This limitation may inhibit the appropriate treatment of vascular disease. Recently, a variety of endovascular tools designed for the treatment of specific disorders have been developed, such as lytic therapy for thrombotic occlusions, lasers for fibrotic occlusions, and atherectomy catheters for calcific atherosclerotic occlusions. For effective use of these tools, the specific cause of a vascular lesion must be determined. Angioscopy can enhance the use of these innovative therapies by providing a real-time panoramic view of the lumen, which permits both the diagnosis of luminal irregularities and visual guidance of specific luminal therapy.