Backgrounds: Multislicie Computed tomography (MSCT) provides accurate noninvasive assessment of coronary artery stenosis as well as detection and characterization of atherosclerotic plaques. The aim of this study was to determine the accuracy of MSCT for characterization of coronary non-calcified plaques and compare the density of it by intravascular ultrasound(IVUS). Methods: The 45 plaques were characterized in 10 patients undergoing MSCT and IVUS. Coronary plaques were classified as hypo-echogenic appearance (n=18) and hyper-echogenic appearance based on the IVUS echogenecity. In MSCT, the CT attenuation was measured using circular regions of interest(ROI) and represented as Hounsfield units(HU). Results : The MSCT density of hypoechogenic appearance was 51.8+36.8HU. The MSCT density within plaque that corresponded to hyper-echogenic appearance was 105.4+54.1HU. There was statistically significant difference in MSCT density in the two groups (p < 0.001). Using a cut-off value of 60.5HU, sensitivity was 82%, and specificity was 72%. However, there was an overlap between the CT attenuation measured in hypo-echogenic and hyper-echogenic appearance within plaques. Conclusions: In our study, mean CT attenuation measured within non-calcified coronary atherosclerotic plaque had significant difference between hypo-echogenic and hyper-echogenic appearance. However, there was an overlap of attenuation values between plaques so that the further evaluation of plaques characterization on MSCT might be needed.