A 63-year-old male underwent elective coronary angiography at our institution. After three attempts to intubate the left coronary artery with an Amplatz catheter, an acute aortic dissection with a supracoronary entry occurred without involvement of the coronary arteries. In an emergency surgical procedure, an aortic valve prosthesis was implanted, and the supracoronary thoracic aorta and half of the aortic arch was replaced. Histology demonstrated myxoid degeneration and a disturbed architecture of the elastic fibers of the aorta. The patient had no features of hereditary connective tissue diseases; furthermore, a skin biopsy revealed no signs of Marfan's or Ehlers Danlos Syndrome.