Carotid duplex ultrasonography (DUS) is routinely performed prior to coronary artery bypass graft surgery (CABG) on all patients > 65 years old because of the reported associated risk of finding concomitant carotid artery stenosis. Identifying risk factors that correlate with severe carotid stenosis may result in more cost-effective screening for patients with asymptomatic carotid artery disease prior to CABG. We performed a retrospective study to identify risk factors for significant carotid artery disease in patients scheduled to undergo CABG between March 2005 and March 2008 at the Massachusetts General Hospital. Patients with carotid stenosis >or= 70% identified by DUS (n = 50) were matched by age and sex to control patients who had < 50% stenosis (n = 50). Data were analyzed using the chi-squared test or analysis of variance as appropriate. Logistic regression was used to examine multivariate correlates of carotid stenosis. A total of 643 patients were screened to arrive at the patient cohorts described below. This produced a prevalence of 7.7% for significant (> 70%) carotid disease. The patient cohorts were predominantly male with no significant difference in the incidence of diabetes, hypertension, extent of coronary artery disease (CAD) (i.e. left main coronary artery disease (LMCA) and one, two-, or three-vessel CAD) or lipid abnormalities in the two groups. Univariate analysis identified the presence of peripheral arterial disease (PAD, p = 0.001), a cervical bruit (p < 0.0001), a prior neurological event (p = 0.020), and the presence of an abdominal aortic aneurysm (AAA; p = 0.046) as significant predictors of >or= 70% internal carotid artery stenosis. Logistic regression analysis revealed that the presence of a carotid bruit (p = 0.0068) and PAD (p = 0.0194) were associated with an increased risk of significant carotid artery disease. In conclusion, the presence of a carotid bruit or PAD predicts an increased likelihood of significant carotid artery disease in patients undergoing CABG. Unlike previous studies, LMCA or extent of CAD did not correlate with significant carotid artery disease. Using these predictive models, a prospective outcomes trial is required to validate these criteria.