Abstract Objective — morphometric analysis in patients with DeBakey type III aortic dissection, to determine correlation between the values and geometric requirements of stent-graft for improvement of the results of thoracic endovascular aortic repair. Material and methods. A retrospective assessment of CT-scans of 106 patients without previous aortic surgery was made using the standard protocol. The following parameters were measured using multiplanar reconstructions: the length of aortic central line (CLAO) and the true lumen central line (CLTL), cross section areas of the aorta and the true lumen at five levels. These results were calculated in diameters of the aorta and true lumen at different levels in 5 points. Values were compared using Student’s t-test or Mann—Whitney U-test, as appropriate. Results. CLAO and CLTL values were similar, but mean length of CLTL was less by 21.3 mm. There was a correlation between gender and length of CLAO and CLTL. CL length was significantly higher in men. Taper ratio in point 2 makes up 56%, in point 3 — 92%, in point 4 — 108%, in point 5 — 98%. Conclusion. It is appropriate to use stent-grafts with length of 250 mm and over and taper difference over 10 mm. Nevertheless, endovascular thoracic aortic repair using these devices requires further researches.