We analyzed six SNPs in enzymes involved in homocysteine metabolism (i.e., MTHFR C677T and A1298C; CBS T833C, G919A and 844ins68, and MS A2756G) in 872 healthy study subjects and studied their influence on the risk of hyperhomocysteinemia in this population. The gene discussed is MTHFR; the disease is hyperhomocysteinemia.