Background: Carotid intima-media thicness(IMT) was widely used as a surrogate of early atherosclerosis. But Patients characteristics in cohort based study of carotid IMT is very heterogenous. We evaluate carotid intima, media and IMT in really ���normal��� subjects who had no coronary artery disease or other coronary risk factors. Methods; Among the 3041 patients(male:female=1819:1222, mean age=61짹11) who underwent carotid ultrasound since 2003, 124 subjects(male:female= 84:40, mean age=54짹12) who had no coronary artery stenosis confirmed by coronary angiography, no diabetes, hypertension, hypercholesterolemia or renal dysfunction were enrolled. Carotid intima, media, IMT was compared between general population group and really normal subjects. Results: Right maximal, mean IMT, intimal thickness, medial thickness was 0.93짹0.25, 0.78짹0.16, 0.24짹0.36, 0.51짹0.15mm in really normal subjects, respectively. Left maximal maximal, mean IMT, intimal thickness, medial thickness was 0.92짹0.33, 0.79짹0.24, 0.23짹0.03, 0.55짹0.24mm. Maximal and mean IMT, Medial thickness at both carotid artery was significantly higher in general population. Conclusion: In large korean cohort for carotid IMT, Carotid medial thickness and IMT was significantly related with atherosclerotic risk factors. It must be careful for defining the normal reference value of carotid IMT due to heterogenous charateristics of population.