OBJECTIVE Carotid artery intima-media thickness (IMT) is now widely used as a surrogate marker for atherosclerotic disease. Carotid IMT measured by ultrasound has been shown to be correlated with coronary artery disease as defined by angiography. However, the relation between carotid IMT and isolated coronary artery ectasia (CAE) has not been investigated. The aim of our study was to assess this relation. METHODS Twenty-five patients with isolated CAE without stenosis and 25 control subjects with angiographically normal coronary arteries were included in this study. These were examined by B-mode ultrasound to measure the IMT at the far wall of the common carotid artery. RESULTS Patients with isolated CAE had significantly higher carotid IMT compared to control subjects with angiographically normal coronary arteries (0.95+/-0.12 versus 0.71+/-0.10mm respectively, p<0.0001). In addition, we detected a significant positive correlation between the presence of CAE and carotid IMT (r=0.748, p<0.001). CONCLUSIONS We have shown for the first time an association between increased carotid IMT and isolated CAE, suggesting that atherosclerosis may be involved in the pathogenesis of isolated CAE in the adult population.