A high plasma concentration of total homocysteine (tHcy) and a deficiency of vitamins related to its metabolism, such as vitamin B12 and folate, have been associated with cardiovascular disease. Postmenopausal women have higher concentrations than age-matched premenopausal women, and plasma concentrations of homocysteine in postmenopausal women taking hormone replacement therapy are significantly lower than they are in those who do not take estrogen supplements. Because of the possible mixed effects of HRT on cardiovascular events, surrogate end-points must be evaluated with caution. While measuring homocysteine levels is relatively simple, evidence from well designed trials is awaited before population screening can be advocated. Also, the benefits of reducing homocysteine levels with folic acid and vitamin B6 and B12 supplements are highly debated.