The authors report an unusual dissecting aneurysm of the left subclavian artery occurring in a patient suffering from the Ehlers-Danlos syndrome. Clinical history and skin biopsy permitted this diagnosis. Surgical treatment associated resection of the aneurysm, ligation of the proximal part of the subclavian artery and a prosthetic bypass between carotid and subclavian artery. Spontaneous dissecting aneurysm is a rare disease and one must think before surgery to arterial dysplasia. Technical features of the surgical treatment are discussed.