Abstract Background: Although degree of coronary luminal nar-rowing continued to guide therapeutic intervention in clinical cardiology, CT coronary angiography provides additional information about atherosclerotic plaque characteristics such as plaque morphology which recently showed good correlation with acute coronary syndrome as an independent factors. Aim of Study: The purpose of the study is to characterize atherosclerotic plaques as regard plaque burden and morpho-logical features to avoid acute coronary syndrome later on. Patients and Methods: 60 patients; 36 patients were with stable coronary artery disease and 22 patients were with unstable coronary artery disease. All patients were scanned first with coronary artery calcium scoring then, contrast enhanced coronary angiography. Coronary CT angiography was evaluated for morphologic features. Results: High risk plaque criteria were identified as NRS, LAP <60, plaque burden >0.7 and R.I >1.1. Characterization of the calcified lesions had the advantage of assessment of post contrast calcium which showed high correlation with pre contrast calcium volume of traditional calcium score as reference (rs=0.97) Hence, accurate detection of the degree of stenosis (p=<0.001). Conclusion: Characterization of coronary plaques by quantitative coronary plaque analysis improved image quality for calcified plaques and correlate well with high risk plaque criteria.