Purpose: Atherosclerotic risk factors are highly associated with the progression and severity of cerebrovascular disease; the carotid artery intima-media thickness (IMT) correlates well with the known risk factors for atherosclerosis. The aims of this study are to evaluate the associations of the carotid artery IMT with the atherosclerotic risk factors and to determine the reference values of the carotid artery IMT in healthy subjects who were without cardiovascular symptoms. Method: Ultrasound high-resolution B-mode imaging of the carotid artery was performed in 273 subjects (168 men, 105 women). We investigated the mean carotid artery IMT and the correlation between the carotid artery IMT and the atherosclerotic risk factors. Result: The mean carotid artery IMT values were 0.70⁑0.25 mm in the common carotid artery, 0.61⁑0.15 mm in the internal carotid artery, 0.55⁑0.26 mm in the external carotid artery and 0.92⁑0.45 mm in the carotid bulb. The mean carotid artery IMT was significantly increased with increasing age (P＜0.05), and particularly in males. Age, systolic and diastolic blood pressure, body mass index, total cholesterol and LDL cholesterol levels correlated with the mean carotid artery IMT. Especially, the presence of plaque (26 subjects) was correlated with the mean carotid artery IMT in the internal carotid artery (P＜0.05) and bulb (P＜0.01). Conclusion: This study revealed the correlation between the carotid artery IMT and the atherosclerotic risk factors; we also elucidated the reference values for the mean carotid artery IMT in healthy subjects who were without cardiovascular diseases and symptoms.