Large artery stiffness is predictive of adverse cardiovascular events and all cause mortality. This book presents a series of in-vivo experimental studies investigating effects of structural and functional changes on large artery stiffness. Novel analysis methods for measurement of arterial stiffness indexes are discussed and applied. Findings in acute inflammation, active and passive changes in systemic pressure, aortic elastic laminae defects, aortic calcification, and vasoconstrictor agents (angiotensin-II, noradrenaline, and endothelin-1) in animal models are reported. The vasodilating properties of the beta-antagonist and nitric oxide donor, nebivolol, is investigated in the human iliac artery. Changes in human forearm arterial stiffness during reactive hyperaemia are studied with respect to the importance in clinical quantification of endothelial dysfunction. Findings across these studies provides new, quantitative contributions to the in-vivo experimental investigation of the aetiology of large artery stiffness related to structure and function of artery wall properties This can lead to potential clinical applications and techniques for assessment of cardiovascular risk.