Soft biological tissues are anisotropic, heterogeneous materials that exhibit viscous and elastic non-linear mechanical properties. In my presentation, I will shed some light on the role of the extracellular matrix in the mechanical properties of the aorta and heart valves. Cardiovascular tissue consists of elastin and collagen fibers, glycosaminoglycans, and cells. Extracellular matrix components play essential roles in tissue remodeling. Collagen fibers have been responsible for the anisotropic behavior and the dispersion and orientation of these fibers have a significant effect on the mechanical response of the tissue. Pathophysiological conditions alters the microstructure and biomechanical response of vascular tissues. My talk mainly focuses on the mechanical property of the aorta and heart valves and investigations on the structure-property relationship of these tissues.