Few studies of progression of atherosclerotic peripheral vascular disease have been performed and none have used objective methods to evaluate disease progression in a large number of symptomatic subjects. The study is of obvious major clinical importance. Elevated plasma homocysteine is well established as an independent risk factor for atherosclerosis. If folate treatment results in less frequent/rapid progression of peripheral vascular disease, then it will be confirmed as the first effective treatment for atherosclerosis which is without toxic side effects and does not involve major changes in life/dietary habits.