A patient with XO Turner's syndrome with a 12-year history of progressive aortic root dilatation resulting in chronic aortic regurgitation is presented. Her case is unique in that it occurred in the absence of coarctation of the aorta, bicuspid aortic valve, or hypertension. Idiopathic dilatation of the aorta may be an additional risk factor to the development of aortic dissection in the setting of Turner's syndrome.