To evaluate the association between common carotid intima-media thickness and noninvasively assessed atherosclerosis elsewhere in the carotid artery, we used data from the Rotterdam Study, a single-center population-based, prospective follow-up study among 7983 subjects aged 55 years or older. Baseline measurements included ultrasonographic evaluation of the vessel wall characteristics of the carotid arteries, that is, assessment of the presence of atherosclerotic lesions, measurement of common carotid intima-media thickness, and determination of the presence of hemodynamically significant stenosis. The present analysis is based on data obtained from the first 1000 participants. The results were adjusted for age and gender. An increase of 1 standard deviation in common carotid intima-media thickness (0.19 mm) doubled the risk of plaques in the carotid bifurcation: odds ratio 2.0 (95% confidence interval (CI): 1.6, 2.4). For hemodynamically significant stenosis of the right internal carotid artery (> or = 50%), a 1.4 (95% CI: 1.0, 2.0) increased risk was found. The risk of atherosclerotic plaques in the bifurcation in subjects with an intima-media thickness above 0.89 mm (upper quintile) relative to those with an intima-media thickness below 0.63 mm (lowest quintile) was 6.0 (95% CI: 3.5, 10.2). For internal carotid artery stenosis, a relative risk of 2.8 (95% CI 0.5, 15.7) was found. The findings of the present study provide evidence that increased common carotid intima-media thickness indicates atherosclerosis at other sites of the carotid artery. This study lends support to the view that noninvasively assessed increased intima-media thickness of the distal common carotid artery is an indicator of generalized atherosclerosis.