Objectives. Bicuspid aortic valve (AV) represents the most common form of congenital AV malformation, which is frequently associated with pathologies of the ascending aorta. We compared the mechanical properties of the aortic wall between patients with bicuspid and tricuspid AV using a new custom-made device mimicking transversal aortic wall shear stress. Methods. Between 03/2010 and 07/2011, 190 consecutive patients undergoing open aortic valve replacement at our institution were prospectively enrolled, presenting either with a bicuspid (group 1, n=44) or a tricuspid (group 2, n=146) AV. Aortic wall specimen were examined with the “dissectometer” resulting in nine specific aortic-wall parameters derived from tensile strength curves (TSC). Results. Patients with a bicuspid AV showed significantly more calcified valves (43.2% versus 15.8%, P