A previously healthy 19-year-old woman died two hours after the sudden onset of severe chest pain. The only gross abnormality seen at the time of autopsy was thrombosis of the left main coronary artery. Microscopic examination of the artery showed eccentric necrotizing arteritis with giant cells, associated with the thrombus. The aorta was infiltrated with lymphocytes, histiocytes, and an occasional giant cell. Sudden cardiac death as the initial manifestation of a giant cell arteritis that involves only the coronary artery and aorta is rare.