Intravascular ultrasound (IVUS) is the generic name for any ultrasound technology used in vivo within the blood vessels. IVUS has been recognized as a sensitive tool to assess the anatomy of the epicardial coronary arteries, including intimal and adventitial wall thickness. The procedure is performed at the time of the routinely schedule angiogram and has been demonstrated to be safe and have reproducible findings. Although quantitative coronary angiography has been used to assess late lumen loss, IVUS provides more detailed and reliable information on the extent and distribution of intimal tissue, the presence of stent under expansion, and vascular remodeling after coronary artery bypass surgery. IVUS could be usefully to analyze both arterial and vein grafts, including radial grafts and to monitoring graft failure.