Rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) are associated with increased mortality, largely as a consequence of cardiovascular disease. Increased cardiovascular morbidity and mortality in patients with RA and SLE cannot be entirely explained by traditional risk factors, suggesting that the systemic inflammation that characterizes these diseases may accelerate atherosclerosis. We used carotid ultrasonography to investigate the prevalence and correlates to preclinical atherosclerosis in patients with RA and SLE. Because atherosclerosis is a systemic disease, assessment of carotid plaque by ultrasonography provides a robust, direct measure of systemic atherosclerosis. We observed a substantially increased prevalence of carotid plaque in RA and SLE patients compared with age- and sex-matched controls, which remained after adjustment for traditional risk factors. The presence of carotid atherosclerosis was associated with disease duration in both RA and SLE and damage in SLE. These data support the hypothesis that inflammation associated with RA and SLE contributes to accelerated atherosclerosis and argue that RA and SLE disease activity should be more aggressively managed.