Research over the past decade has shown that elevated levels of homocysteine have a strong association with all forms of atherothrombotic disease and venous thromboembolism. This association is particularly strong for coronary disease and newer data indicate that screening for homocysteine levels may be warranted in those with unexplained thrombotic tendencies and in young patients who develop coronary events or disease without the usual predisposing factors such as hypertension, smoking, hypercholesterolemia, or diabetes. Although the link between hyperhomocysteinemia and cardiac disease has not been conclusively shown to be causal as yet, data are emerging that lowering homocysteine levels may be beneficial in patients at high risk. Such lowering can be done safely and inexpensively with increased intake of fruits and vegetables and in those patients who are particularly at high risk using supplementation with folic acid and the B vitamins. Preliminary studies have shown that lowering homocysteine levels in this manner may slow the progression of atherosclerosis in coronary and carotid vessels. No mortality data exist yet showing that reducing homocysteine reduces cardiac or total mortality, although it is likely that ongoing and planned trials that are underway will shed light on these important questions soon.