Ethnic differences in non-invasive measures of atherosclerosis are increasingly being reported, but the relationship of these measures to each other has not been widely explored. Carotid ultrasonographic and computed cardiac tomographic findings were compared in 6814 participants of White, Black, Hispanic, and Chinese ethnicities free of overt cardiovascular disease. Coronary calcium and carotid atherosclerosis were strongly related to each other in all ethnic groups. Associations of coronary calcium prevalence and common carotid intimal-medial thickness (IMT) differed by ethnicity in women, being weakest among Black women (0.07 mm IMT difference between those with and without coronary calcium) compared to the other three groups (0.10-0.12 mm difference, p=0.007). Estimated percent increments in internal carotid IMT per 10% increment in coronary calcium score were highest in Hispanics (18.5%) and lowest in Blacks (6.1%, p<0.01). Coronary calcium may be less strongly associated with carotid atherosclerosis in Blacks, particularly Black women, than in other ethnic groups. These differences should be pursued for relationships to coronary events to determine whether coronary calcium carries the same risk information in other ethnic groups as it does in Whites.