Although it was initially thought that folate deficiencies are uncommon in the elderly, the use of the. plasma total homocysteine concentration as a metabolic marker of folate status is changing this attitude. Plasma homocysteine measurements in epidemiological studies suggest that subclinical folate deficiencies are common in various populations, including the elderly. The clinical consequences of a compromised folate status may include increased coronary heart disease and cancer risk, and an association between folate deficiency and neuropsychiatric illness has been reported. Although a suboptimal folate status is associated with at least 2 major chronic diseases, it would he premature to recommend folate supplements to all elderly people. We still lack evidence that a suboptimal folate status is causally involved in the pathogenesis of the abovementioned disorders. Furthermore, cancer and the cardiovascular diseases are chronic conditions and it may be too late to use folate supplementation as preventative measures in elderly persons. However, folate supplementation should be considered in elderly people with elevated plasma total homocysteine concentrations and proven cardiovascular disease, in elderly patients treated with drugs known to induce a folate deficiency, and in those who experience neuropsychiatric disorders. Cyanocobalamin (vitamin B12) deficiencies should be excluded before folate supplementation is commenced; if in doubt, it may be safer to supplement folate and vitamin B12 together. The daily folate supplement should be at least 0.5 mg/day and it should never be used as a surrogate for a diet rich in fruit and vegetables.