Background: Significant atherosclerotic plaque burden in conjunction with plaque vulnerability in left main (LM) and ostial left anterior descending artery (LAD) may play an important role in development of clinically significant LM and LAD ostial disease. We investigated the distribution of plaque burden from LM to distal LAD in a series of Asian population who had angiographically normal coronary arteries. Methods: Patients (pts) with atypical anginal symptoms who underwent diagnostic coronary angiography with acetylcholine (Ach) provocation test and in whom angiographically normal LM and LAD were selected for volumetric intravascular ultrasound (IVUS) examination using MIA program (INDEC). Results: A total 89 patients (pts; 42 men, mean age; 54.1짹10.8 years) were enrolled for the study. Pts were categorized with every decades of age and mean plaque volumes are measured (Table). Mean plaque volume in LM, LAD os and proximal LAD were 19.3짹11.1%, 17.4짹10.8% and 23.0짹13.5%, respectively. Plaque burdens were increased from LAD distal to LM in every decade. Specifically, plaque burdens in LM and LAD os correlated with increasing age (r=0.307, p=0.003 for left main, r=0.283, p=0.007 for LAD os). Conclusion: In pts with angiographically normal appearing coronary arteries in a series of Asian population, detailed volumetric measurements using IVUS showed considerable amount of atherosclerotic plaque burdens in LM and ostial LAD and these plaque burdens are increased with aging and from distal to proximal coronary arteries.