The present study examined the association between carotid intima-media thickness (IMT) and severity and extent of coronary artery disease (CAD). B-mode ultrasound and quantitative coronary angiography were used to assess carotid and coronary artery atherosclerosis in 108 patients with known or suspected CAD who had been referred for cardiac catheterization. Maximum and mean IMT values of carotid arteries were measured and expressed as mean aggregate values. To evaluate anatomic severity and extent of CAD, several quantitative coronary angiographically derived parameters were incorporated into indexes. These quantitative coronary angiographic measurements reflected CAD severity, extent, and overall "atheroma burden" and were calculated for the entire coronary tree and separately for different coronary segments (i.e., left main, proximal, mid, and distal segments). Maximum and mean IMT values were significantly correlated with CAD severity (p = 0.004 and 0.005, respectively), extent (p = 0.022 and 0.016, respectively), and atheroma burden (p = 0.008 for the 2 values). Further, carotid IMT was correlated with quantitative angiographic indexes for mid and distal segments but not with the proximal segments of coronary vessels. In conclusion, our study shows an association between carotid IMT and severity and extent of CAD as assessed by quantitative coronary angiography. Carotid IMT seems to be a weaker predictor of coronary atherosclerosis in the proximal parts of the coronary tree than in the mid and distal parts.