Bacground/Aim. Vast majority of patients with corotid artery sclerosis do not have transitory ischemic attacks (TIA) as working to the persistent silent disease, but stroke is the first sign. Precise and early diagnosis of the carotid artery disease and plaques are very important. The aim of this study was to determine how the composition / identity of diagnostic methods, color-Doppler, ultrasonography (US) CT multidetector angio (MDCTA) scan and intraoperative (IO) findings, as well as the morphology of plaques in patients with haemodynamic significant stenosis of the internal carotid artery. Methods. Carotid plaques were observed by two diagnostic methods, US and MDCTA, and these findings were correlated with the IO findings. Results. In 62 patients both carotid artheries were examined and 83 plaques were observed. There were 68 surgical interventions. The structure of plaques was divided into four types: lipid, fibrous, fibrocalcified and calcified plaque. US showed: lipid plaques 10.8%; fibrous 1.2%; fibrocalcified 44.6% and calcified 43.4%, and the MDCTA lipid plaques 8.4%; fibrocalcified 48.2% and calcified 43.4%. Intraoperative findings were: lipid plaques 10.3%; fibrocalcified 41.2% and calcified 48.5%. A statistically highly significant agreement between the US and MDCTA in the diagnosis of plaque morphology was obtained (Cramer's V = 0.919, p < 0.01; Lambda = 0.921, p < 0.01) and also statistically significant agreement between US and IO findings (Cramer' s V = 0.831, p < 0.01; Lambda = 0.859, p < 0.01). A statistically highly significant agreement between MDCTA and IO findings in plaque morphology was found, as well (Cramer's V = 0.815, p < 0.01; Lambda = 0.829, p < 0.01). Conclusion. There is statistically highly significant correlation between US and MDCTA diagnostic methods in the evaluation of plaque morphology in surgically significant stenosis of internal carotid artery as well as their agreement with the intraoperative finding.