Increased arterial stiffness is associated with ageing, cardiovascular disease diabetes and renal failure. The aims of this thesis were to investigate the reproducibility of a tissue Doppler imaging (TDI) based ultrasound system to calculate indices of arterial stiffness, and to investigate changes in arterial wall stiffness in subjects with increased age, peripheral arterial disease (PAD), chronic kidney disease (CKD) and angiotensin converting enzyme inhibitors (ACE-Is). A reproducibility study demonstrated good reproducibility. A study of healthy subjects demonstrated a stronger relationship with age for arterial stiffness than intima media thickness (IMT). Case control studies investigating changes in subjects with PAD and CKD demonstrated a greater increase in arterial stiffness than IMT when compared to healthy controls. An epidemiological study, investigating the effect of antihypertensives on collagen turnover, suggested an association between increased collagen turnover and ACE-Is. Investigating the effect of ACE-I administration on arterial stiffness in subjects with PAD, we demonstrated an increase in collagen turnover and a decrease in arterial stiffness. We have demonstrated that the TDI-based system is a reproducible method of measuring arterial stiffness. We suggest that arterial stiffness increases more than IMT with ageing, PAD and CKD and that it may increase before cardiovascular disease develops.