Peripheral arterial disease (PAD) is a common disease. There is substantial evidence that hyperhomocystelnaemia is associated with an increased risk of developing coronary and cerebral artery disease but little is known about hyperhomocysteinaemia, folate supplementation and PAD. This thesis presents the results of original PAD studies on the association of hyperhomocysteinaemia and homocysteine (Hey) genetic mutations; the role of folate therapy; and risk biomarkers, photoplethysmography (PPG) and pulse wave velocity (PVW) as novel techniques In assessing PAD severity. : A meta-analysis of 14 previous studies showed that raised concentrations of plasma tHcy were significantly associated with an increased risk of PAD.