Using B-mode ultrasound,we studied the prevalence of abdominal aortic aneurysm(AAA; diameter< 3 cm) and its predictive risk factors in 109 consecutive patients who were >60 years of age and had coronary artery disease(CAD). A group of 60 age-matched patients who did not have CAD served as controls. The prevalence of AAA was higher in the CAD group than in the control group(14% , 16 of 109, vs 3% , 2 of 60, p< 0.05). By multivariate analysis, only smoking was strongly associated with AAA(odds ratio 4.86, 95% confidence interval 1.55 to 15.25). In contrast, presence of diabetes mellitus was negatively associated with AAA in univariate analysis(odds ratio 0.11, 95% confidence interval 0.01 to 0.83) and a strong trend of inverse association remained in multivariate analysis(odds ratio 0.12, 95% confidence interval 0.01 to 1.03). Thus, systematic screening can detect AAA in 1 of 7 patients who are >60 years of age and have CAD. AAA shares some, but not all, risk factors of atherosclerosis.