ALT In total, 105 adults undergoing elective ascending aortic replacement in the setting of bicuspid aortic valve were enrolled. The aorta was resected en bloc and cut into specimens for uniaxial or biaxial testing from the aortic root, proximal, middle, and/or distal ascending regions. Age, ascending aortic length, and maximum ascending aortic diameter appeared the most frequently in variable importance plots denoting contribution to models of physiologic and failure metrics. We conclude that aortic tissue stiffens, withstands lower wall stress, and weakens with age. Bicuspid aortopathy phenotype and valve morphology were not associated with mechanical behavior. VIMP, Variable importance.