PURPOSE: Homocysteine is a known independent risk factor for cardiovascular diseases and its blood levels are influenced by several factors such as race, diet, and lifestyle, so on. Considering these factors, the normal value for total homocysteine has not been determined in Korea. The objective of this study is to establish the normal value for serum total homocysteine and elucidate the prevalence rate of hyperhomocysteinemia by gender and age. SUBJECTS AND METHODS: Among the participants of a community-based cohort study conducted in Yangpyeong province, 889 subjects were measured the biochemical analytes including homocysteine. Those who had the medical histories of angina, myocardial infarction and/orstroke, those who had low levels of folate and/or vitamin B12 and those who had high creatinine level were excluded. Finally, 506 subjects were selected as the reference population. A normal value was established with Clinical and Laboratory Standards Institute C28-A2 protocol. RESULTS: Homocysteine concentrations of total 889 population and 506 reference population were 10.3+/-5.7 micromol/L (1.9 ~ 93.9 micromol/L) and 8.8+/-2.5 micromol/L (4.3 ~ 21.4 micromol/L), respectively. Homocysteine level was significantly higher in men compared to women (P<0.001) and was significantly increased with age. Normal values were 6.7~15.3micromol/L for men and 5.2~12.7 micromol/L for women. With the normal values, the prevalence rates of hyperhomocysteinemia were 13.3% for men and 8.5% for women in total 889 population. The prevalence rate was highest for individuals aged 60 years or older. CONCLUSIONS: These data on homocysteine concentrations are similar to from different countries. The established normal value might be used to evaluate quantitatively the risk for hyperhomocysteinemia.