The authors report another case of rupture of the thoracic aorta in Giant Cell arteritis. The progressive nature of the rupture enabled life-saving aortic replacement with a vascular prosthesis. Only one previous report of this type of operation was found in a search of the literature. The prevalence of aortitis in Giant Cell arteritis would appear to be underestimated after autopsy studies. It affects the thoracic aorta mainly in the ascending segment but sometimes involves the whole aorta. It may remain asymptomatic or be complicated by arterial occlusion, aortic regurgitation, aneurysm, dissection or rupture. Effective steroid therapy could prevent these complications.