Low socioeconomic status (SES) is associated with poor health outcomes in patients who have coronary heart disease (CHD). Inflammation is a potential mechanism by which low SES may lead to adverse cardiovascular outcomes, but it is not known whether low SES is associated with inflammation in patients who have CHD. We measured high-sensitivity C-reactive protein (CRP) levels in a cross-sectional study of 985 adults who had CHD. Income and education were determined by self-report. We used ordinal logistic regression to examine the association of income and education with CRP. Of the 985 participants, 390 had high CRP levels (>3 mg/dl). The proportion of participants who had high CRP levels ranged from 30% (103 of 340) in those who had a college degree to 51% (65 of 127) in those who had less than a high school degree (p<0.0001). The proportion of subjects who had a high CRP level ranged from 28% (52 of 183) in those who had annual income>or=$50,000 to 42% (199 of 974) in those who had an annual income<$20,000 (p<0.001). After adjustment for traditional cardiovascular risk factors and other potential confounding variables, lower income and education remained associated with higher CRP levels. In conclusion, low SES is associated with high CRP levels in patients who have CHD. This observation raises the possibility that inflammation may contribute to the adverse cardiovascular outcomes associated with low SES.