The association of apolipoproteins A-I and B (apo A-I and apo B) with cardiovascular disease has been studied in younger populations, but there is sparse information in the elderly. We determined whether apo A-I and apo B were associated with carotid artery atherosclerosis (CAA) in 507 stroke-free elderly community residents (mean age 70.1+/-11.7 years, 60% women, 41% Hispanics, 30% African American, 28% Caucasian). CAA severity was normal (no plaque or carotid stenosis) in 39%, mild (maximum plaque thickness < or =1.8 mm or carotid stenosis <40%) in 25%, and moderate/severe (maximum plaque thickness >1.8 mm or carotid stenosis > or =40%) in 36%. CAA severity increased with age in all race/ethnic groups (P<0.01). CAA was similar among African Americans and Caucasians, but less in Hispanics (age adjusted OR: 0.5, CI: 0.4-0.8). apo A-I <1.2 g/l (OR: 2.0, CI: 1.0-3.3) and apo B > or =1.4 g/l (OR: 2.0, CI: 1.1-3.6) were associated with moderate-severe CAA. An apo B/apo A-I ratio > or =1 was associated with moderate-severe CAA (OR: 2.4, CI: 1.3-4.4), and the association varied by race (Hispanics OR: 4.3, CI: 1.8-10; non-Hispanics, OR: 1.4, CI: 0.6-3.2). Total cholesterol, triglycerides and low density lipoprotein cholesterol were not associated with moderate-severe CAA, while high density lipoprotein cholesterol was protective (OR: 0.4, CI: 0.2-0.8). Thus, in an elderly population, apo A-I and B were determinants of moderate-severe CAA, and the degree of association varied by race/ethnicity