The aim of this study was to assess the relationship between the plaque burden of nonstenotic coronary artery segments and the wall thickness of peripheral arteries using intracoronary and transcutaneous ultrasound imaging, respectively. Intracoronary ultrasound (CVIS, 3.5 Fr) was performed in 27 patients undergoing percutaneous transluminal coronary angioplasty. Carotid arteries were imaged by B-mode ultrasound with semiautomatic edge detection and radial arteries by high resolution A-mode echotracking (NIUS 2). Quantitative measurements included coronary artery intima-media cross-sectional area (IM(CSA)) and cross-sectional narrowing (CSN), as well as intima-media thickness (IMT) and lumen radius (r) of the common carotid and the radial arteries. Intima-media thickness was increased in coronary, carotid, and radial arteries. Coronary arteries had an IM(CSA) of 7.7 +/- 2.5 mm(2) and a CSN of 24% +/- 8%. Despite this moderate plaque burden, lumen area was preserved (12.3 +/- 4.2 mm(2)) because of compensatory enlargement of coronary arteries. Right and left carotid and right radial arteries had an IMT of 575 +/- 78 microm, 570 +/- 129 microm, and 328 +/- 61 microm, respectively. There was no correlation between coronary IM(CSA) and carotid IMT (r = 0.07) or radial IMT (r = 0.02), and there was no correlation between coronary CSN and carotid IMT/r (r = 0.12), or radial IMT/r (r = 0.25). In conclusion, in these patients with symptomatic ischemic disease no relationship between IMT of the coronary arteries and IMT of carotid or radial arteries was found. Although increasingly popular, IMT of peripheral arteries may be of limited value as surrogate marker for the severity of coronary artery disease. Cathet. Cardiovasc. Intervent. 48:12-17, 1999.