Aim: Recent clinical studies using intra-vascular ultrasound have clarified that coronary artery plaque already exists in subjects with normal coronary artery which is diagnosed by coronary angiography; furthermore, culprit lesion on acute coronary syndrome often occurs in mild to moderate angiographical stenotic lesion. The aim of this study is to clarify relationship between metabolic syndrome and early stage coronary atherosclerosis using a 3-dimensional intra-vascular ultrasound. Methods: 70 subjects with normal coronary artery diagnosed by coronary angiography were enrolled. Proxymal range of left anterior descending coronary artery was observed by intra-vascular ultrasound using autopullback methods. Results: Subjects with metabolic syndrome had significantly high percent plaque volume (31 8% vs 21 8%, p 0.0001) and frequently detected abnormal plaque quality such as eccentricity, calcification and lipid pool into plaque than those without metabolic syndrome. Multivariate analysis showed that serum adiponectin concentration was the most strongest variable for percent plaque volume (t value 3.0, p 0.01). On the other hand, subjects with hypoadiponectinemia were detected high incidence of mild calcification into plaque.