Objectives: Although an absence of coronary artery calcium (CAC) has been known to be associated with very low event rates, non-calcified plaque (NCP) identified by coronary CT angiography (CCTA) has been reported in up to 10% of individuals with zero or low CAC, concerning the prognostic value of a zero calcium in certain patient population. In this study, we sought to investigate the prevalence, clinical characteristics and prognostic implication of NCP based on symptomatic status in a large cohort of subjects with absence of CAC. Methods: The study population consisted of consecutive asymptomatic or atypical chest pain subjects (52 짹 10 years, 61% men) who underwent CCTA (64-slice MSCT) from Dec 2005 to Jan 2008. We analyzed the prevalence of NCP with absence of CAC and their clinical characteristics and prognosis were compared with age, sex and symptom status-matched control without NCP and CAC. Results: Overall, 5.9% (n=471) of total subjects (n=7920) and 7.7% of subjects with absence of CAC (n=6148) had NCP with absence of CAC. There was no difference in the prevalence of NCP with absence of CAC according to symptom (asymptomatic vs atypical chest pain: 6.1% vs 5.6%, p= 0.23, respectively). Among subjects with NCP with absence of CAC, sixty one (13%) subjects had significant (���50%) diameter stenosis.The prevalence of significant stenosis was higher in subjects with atypical chest pain (asymptomatic vs atypical chest pain: 10.5 % vs 19.0% (p=0.01)). In comparison with age, sex, symptom matched control without NCP nor CAC, hypertension (OR 1.53; 95% CI1.11-2.11, p=0.01), diabetes (OR 1.88; 95% CI 1.13-3.11, p=0.01), and dyslipidemia (OR 2.18; 95% CI 1.30-3.67, p=0.003) were significant predictors for NCP in multivariate logistic regression. Midterm follow-up (23 짹 6 months, follow-up rate: 92%) of subjects with NCP (n= 471) and subjects with control group (n=471), there was no clinical event including cardiac death, myocardial infarct, and unstable angina requiring hospitalization. Revascularization procedures in subjects with atypical symptom (n=11) and without symptom (n=4) were performed, and all of them were subjects with significant stenosis. However, all of which occurred within 30 days of index visit based on CCTA results. Conclusions: In the largest series of individuals with absent CAC undergoing CCTA, we demonstrate a negligible risk of exclusively NCP. Our findings suggest that in absence of CAC among asymptomatics or subjects with atypical symptom, there is no justification to pursue dedicated assessments of coronary artery with CCTA, resulting in added radiation and contrast exposure.