PURPOSE The purpose of this study is (a) to investigate the prevalence and severity of noncalcified coronary plaque (NCP) using by coronary CT angiography (CCTA) and (b) to analyze predictors of NCP for risk stratification in asymptomatic subjects with low coronary artery calcium scoring (CACS). MATERIALS AND METHODS We enrolled 7515 asymptomatic subjects (4751 men, 2764 women; mean age 51.4짹 10.0 years) who had underwent both CACS and CCTA. The presence of plaque, severity of stenosis, plaques characteristics including NCP and CACS were assessed by MDCT. Patients were categorized as having 0 CACS (6038 subjects) or low CACS (707 subjects; men with CACS from 1 to 50 and women with scores from 1 to 10). We also evaluated conventional risk factors to assess predictors for the presence of NCP in asymptomatic subjects with low CACS. RESULTS CCTA revealed atherosclerotic plaques in 1894 (25.2%), and 371 (5.2%) subjects had a significant (��� 50%) stenosis on CCTA. NCP was detected in 429 out of 6038 patients ( 7.1%) with 0 CACS and 223 out of 707 patients ( 31.5%) with low CACS (p < 0.05). Comparing to subjects with 0 CACS, those with low CACS had markedly increased rates of significant stenosis caused by NCP (0.9% vs 7.5%, p <0.05). In the low CACS group, independent predictors for presence of NCP were male gender, lower HDL cholesterol, diabetes and hypertension comparing to subjects without NCP (all p < 0.05). DM (p=0.030) and hypertension (p< 0.01) were independent risk factors for NCP with significant stenosis. 35 (66.0%) subjects with significant stenosis were classified into low to intermediate risk by NCEP guidelines, which was more pronounced in young adults than in older ones (52.8 짹 11.3 yrs vs. 58.7짹8.7 yrs). CONCLUSION The prevalence and severity of NCP in asymptomatic subjects with low CACS is not negligible. Comparing to subjects with 0 CACS, low but detectable CACS is significantly less reliable in predicting the presence or severity of underlying NCP in especially young asymptomatic subjects.