The aim of the present study was to explore the influence of age and gender, on the association between the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and plasma total homocysteine (tHcy) concentrations in patients with cardiovascular disease (CVD). Fasting tHcy and the MTHFR C677T mutation were evaluated in 98 patients with CVD, 46 were men and 52 women (aged 20-96 years). There was a significant elevation of plasma tHcy with age (75 yr: 43.6 μmol/L; p 55yr: 42.45 μmol/L; p 0.01). However, the plasma tHcy was not increased with older age in women. The frequency of the TT genotype was 19.6% in the younger patients group (>55 yr) compared with 4.7% in the older patients group (>55 yr; p 55 yr). Then, the MTHFR mutation does not seem to be associated with either high tHcy or the occurrence of CVD.