Periodontitis has been linked to clinical cardiovascular disease but not to subclinical atherosclerosis. The purpose of this study was to determine whether periodontitis is associated with carotid artery intima-media wall thickness (IMT). Cross-sectional data on 6017 persons aged 52 to 75 years were obtained from the Atherosclerosis Risk in Communities Study 1996 to 1998 examination. The dependent variable was carotid IMT ≥1 mm. Periodontitis was defined by extent of attachment loss ≥3 mm: none/mild (<10%), moderate (10% to <30%), or severe (≥30%). Covariates included age, sex, diabetes, LDL cholesterol, HDL cholesterol, triglycerides, hypertension, smoking, waist-hip ratio, education, and race/study center. Odds of IMT ≥1 mm were higher for severe periodontitis (OR 2.09, 95% CI 1.73 to 2.53) and moderate periodontitis (OR 1.40, CI 1.17 to 1.67) compared with no periodontitis. In a multivariable logistic regression model, severe periodontitis (OR 1.31, CI 1.03 to 1.66) was associated with IMT ≥1 mm, while adjusting for the other factors in the model. These results provide the first indication that periodontitis may play a role in the pathogenesis of atheroma formation, as well as in cardiovascular events.