Homocysteine exists in plasma as protein-bound and, so-called, free forms. About 70 percent of the total plasma homocysteine is bound to albumin. The free forms include homocystine (homocysteine disulphide) and mixed disulphide. Just minute amounts of reduced homocysteine are found in plasma. Total homocysteine in Plasma, including protein-bound and free forms, has been referred as homocyst(e)ine [H(e)]. Studies for peripheral vascular, cerebrovascular and coronary artery disease (CAD), evaluating H(e) as a cardiovascular risk factor, have been consistently demonstrated that there are more persons with high H(e) among patients than among healthy persons. Increased concentrations of free forms of homocysteine have also generally been reported among patients with occlusive artery disease, with one notable exception of a negative finding in relation to CAD.