To compare the possibilities and limitations of the two-dimensional (2D) and three-dimensional (3D) multiplane transesophageal echocardiography (TEE) for the diagnosis of the thoracic aorta (TA) atherosclerosis stage, qualitative and quantitative assessment of aortic atheromas and coronary atherosclerosis prediction. Materials and methods. 2D and 3D multiplane TEE of the TA was performed in 180 consecutive CAD patients (104 men, 76 women, mean age 62,4±7,5 years) using Philips IE33 xMatrix system and a X7-2t multiplane probe. Ascending aorta, accessible parts of the arch and descending TA were visualized in 2D mode with standard protocol using Live xPlane mode. 3D study of TA was performed using Live 3D and Full Volume modes. 2D and 3D studies were recorded as video clips series on a system hard drive with subsequent off line processing on a QLab 10.8 (Philips) workstation. Qualitative and quantitative assessment of every atheroma was performed using 2D and 3D modes. The degree of severity and distribution of the TA atheromatosis was evaluated according to the classification of ASE and EACVI (2015): grade 0 - intimal-medial thickness ≤1 mm, 1 - intimal thickness ≤2 mm, 2 - focal or diffuse intimal thickening of 2-3 mm (small atheromas), 3 - atheromas >3-5 mm (no mobile/ulcerated components), 4 - atheromas > 5 mm (no mobile/ulcerated components), 5 - grade 2, 3, or 4 atheromas plus mobile or ulcerated components. After TEE all patients underwent digital coronary angiography. SYNTAX Score was calculated in 122 (67,7%) patients with no coronary stents and bypass grafts. Results. 620 atheromas were analysed: 109 (17,6%) in the ascending part, 8 (1,3%) in the arch and 503 (81,1%) in the descending part. On average 3,4±2,1 atheromas per patient were revealed. Atheromas height in 3D was significantly higher (p<0,001), than in 2D, being 0,38±0,09 cm and 0,26±0,07 cm, respectively. Averaged atheromas height increase in 3D was 0,12±0,06 cm. In 3D 87,7% of atheromas have shown irregular contours while in 2D only 35,4% of atheromas had rough countors. The mobile component in 6 (66,6%) out of 9 atheromas was revealed only in 3D. In 2D 1-5 stages of TA atheromatosis were revealed in 22 (12,2%), 103 (57,2%), 43 (23,9%), 7 (3,9%) and 4 (2,2%) cases, respectively. In 3D 1-5 stages of TA atheromatosis were revealed in 16 (8,9%), 25 (13,9%), 90 (50%), 38 (21,1%) and 10 (5,5%) cases, respectively. With 3D TEE 130 (72,2%) patients were found to have higher gradation of TA atheromatosis stage. TA atheromatosis was not detected in 1 (0,6%) patient. The direct Spearman's correlation between a stage of TA atheromatosis and SYNTAX Score which has been established for 2D rs =0,32 p<0,001 and 3D rs =0,30, p<0,01, respectively. Conclusion. A comparison between 2D and 3D TEE has shown, that 3D is more precise method of qualitative and quantitative assessment of aortic atheromas and diagnosis of TA atheromatosis stage which allows, ultimately, to change the stage of TA atheromatosis towards a higher gradation. 3D ultrasound stage of TA atheromatosis is a surrogate marker of the severity and prevalence of coronary atherosclerosis.