BACKGROUND: Hyperhomocysteinemia as a risk factor for cerebrovascular disease is well known. Our aim of this study was to demonstrate positive association between elevated homocysteine levels and cerebrovascular diseases in Koreans. METHODS: With a case-control design, 186 stroke (infarction 134, hemorrhage 52) patients, diagnosed by brain CT or MRI and 359 control patients were evaluated. We used multiple logistic regression analyses conditioned on the matching variables (sex, age, hypertension, DM, smoking, hyperlipidemia, hyperhomocysteinemia) and calculated odds ratio and 95% CIs. RESULTS: Multivariated adjusted odds ratios (OR) for cerebrovascular diseases associated with hypertension compared with normal blood pressure were 2.45 (95% CI, 1.16 to 5.15) in prehypertension and 3.33 (95% CI, 1.56 to 7.10) in stage 1 hypertension and 3.77 (95% CI, 1.32 to 10.74) in stage 2 hypertension. OR for cerebrovascular diseases associated with hyperhomocysteinemia compared with <10micromol/L were 2.06 (95% CI, 1.09 to 3.91) in 13.0 to 16.9micromol/L and 3.17 (95% CI, 1.70 to 5.90) in > or =17 micromol/L. CONCLUSION: Not only hypertension but also hyperhomocysteinemia was a significant risk factor for cerebrovascular diseases in Koreans.