Objective: This study was planned to investigate the relationship between slow coronary flow and the carotid artery intima-media thickness (CIMT) which is an indicator of early atherosclerotic changes in vascular tree. Methods: Consecutive patients (n=203) who were free of any coronary lesions in coronary angiograms were enrolled. The patients were assigned into slow flow (97) and normal flow (106) groups according to the corrected TIMI frame count (CTFC) of every three coronary arteries. Carotid artery intima-media thickness was measured via computer software regarding far-wall method in both common carotid arteries. Maximum and mean CIMT values were compared between the two groups. The accuracy of CIMT in the prediction of slow coronary flow was estimated using Receiver Operating Characteristic curve (ROC) analysis. Results: Maximum and mean CIMT values were 0.814±0.106 mm and 0.668±0.080 mm for normal flow group and 0.966±0.133 mm and 0.780±0.105 mm for slow flow group respectively (p< 0.001). Using 0.861 as the cut-off value for maximum CIMT positive and negative predictive values of slow flow were 80.1% and 70.2% (area under the ROC curve = 0.809; p <0.001; 95% CI 0.750 – 0.868). Conclusions: We find out that CIMT and CTFC are strongly correlated. This implies that slow coronary flow could be an early marker of subclinical atherosclerosis. So patients with slow flow should be followed-up prospectively for possibility of manifest atherosclerosis.