Backgrounds: Feasibility of coronary CT angiography (CCTA) in intermediate coronary artery disease is not well elucidated. The purpose of this study was to evaluate the feasibility of CCTA in intermediate coronary artery disease by comparing with fractional flow reserve (FFR). Methods: We enrolled 109 Patients (129 lesions) with intermediate coronary artery disease who underwent CCTA and conventional coronary angiography (CAG) with FFR retrospectively. Intermediate coronary artery disease was defined as 30~70% diameter stenosis (DS, %) assessed by CAG, and functionally significant stenosis was defined as FFR <0.8. Maximal hyperemia was induced by intracoronary continuous adenosine infusion using microcatheter. CCTA measurements included diameter stenosis and Agatston calcium score. We divided the patients into 2 groups according to Agatston calcium score for evaluation of calcium score effect assessing stenosis severity (group A: calcium score<100, n= 64, group B: calcium score���100, n=65). Results: In intermediate coronary artery lesions, there was a weak negative correlation between FFR and DS assessed by CCTA (r= -0.248, p= 0.005), whereas there was a moderate correlation between FFR vs. DS assessed by CAG (r= -0.373, p<0.001) and FFR vs. minimal luminal diameter assessed by CAG (r=0.400, p<0.001). The best cut-off value of DS assessed by CCTA to predict FFR<0.8 was >57.2% (47.3% sensitivity, 68.9% specificity, area under the ROC curve (AUC) = 0.583, 95% CI= 0.493-0.669). The accuracy of CCTA to predict FFR<0.8 was not different between 2 groups (group A: AUC= 0.576, 95% CI= 0.446-0.699 vs. group B: AUC= 0.595, 95% CI= 0.466-0.715). Conclusions: CCTA may not be useful to predict the functional significance of stenosis severity in patients with intermediate coronary artery disease.