In a 23 year old female patient, hospitalized at the internal ward for precollapse condition in tachyarrhythmia seizure with signs of the Turner's syndrome and a corresponding chromosomal finding, a radiographic examination of thorax revealed, beside a spine deformity with a marked scoliosis, a spindle-like aneurysmatic dilatation of aortic arc. The duplication of its contour indicated suspected beginning dissection. The further course did not confirm it, though. The possibility of excluding atherosclerotic and luetic etiology of the aneurysm makes it possible to consider the Erdheim's cystic medionecrosis of aorta, which accompanies more frequently the Marfan's syndrome, whereas in the Turner's syndrome it has been reported exceptionally.