BACKGROUND: Few studies to date have described the prevalence of electrocardiographic (ECG) abnormalities in a biracial middle-aged cohort. METHODS AND RESULTS: Participants underwent measurement of traditional risk factors and 12-lead ECGs coded using both Minnesota Code and Novacode criteria. Among 2585 participants, of whom 57% were women and 44% were black (mean age 45 years), the prevalence of major and minor abnormalities was significantly higher (all P < .001) among black men and women compared to whites. These differences were primarily due to higher QRS voltage and ST/T-wave abnormalities among blacks. There was also a higher prevalence of Q waves (Minnesota Code 1-1, 1-2, 1-3) than described by previous studies. These racial differences remained after multivariate adjustment for traditional cardiovascular (CV) risk factors. CONCLUSIONS: Black men and women have a significantly higher prevalence of ECG abnormalities, independent of traditional cardiovascular risk factors, than whites in a contemporary cohort of middle-aged participants.