The purpose of this study was to compare thoracic aortic pathologies of 30 patients with Marfan's syndrome and a group of 78 patients with arterial hypertension. With a mean age of 35 +/- 12 years, patients with Marfan's syndrome were younger than hypertensives (59 +/- 11) (p < 0.01) and Marfan's syndrome, women (52%) were more frequently affected than in hypertensive patients (21%; p < 0.05). While aortic dissection and intramural hemorrhage in patients with Marfan's syndrome were usually confined to the ascending thoracic aorta (62%), in the hypertensive patients aortic disease frequently extended to distal segments of the thoracic or abdominal aorta (p < 0.05). Aortic pathology was complicated by aortic regurgitation in 95% of the patients with Marfan's syndrome and in 56% of the hypertensive patients (p < 0.01). Signs of renal, mesenteric or coronary malperfusion, cardiac effusion and severe hypotension (p < 0.05) were more frequently seen in the hypertensive group. While there was no early death in the Marfan group, only 67% of the patients having aortic dissection or intramural hematoma survived the first 30 days in the hypertensive group (p < 0.01). Aortic dissection, intramural hematoma and aortic aneurysms were as often found in the Marfan's syndrome patients with 60%, 10%, and 30%, as in patients with arterial hypertension with 55%, 6%, and 38% (n.s.). One-year survival rates were high in patients with Marfan's syndrome (93%) as well as in patients with arterial hypertension (73%) (n.s.). The diagnosis of aortic dissection, intramural hematoma, and aneurysms could in all cases be established by the use of noninvasive imaging techniques, such as TEE, XCT, and MRI. Moreover, noninvasive imaging modalities were both highly sensitive and specific for the diagnosis of aortic regurgitation, pericardial effusion, or mediastinal hematoma complicating acute aortic disease.