A serum homocysteine level of >10 μmol/L is called an elevated homocysteine level. The causes of elevated serum homocysteine levels are mainly due to folic acid deficiency or abnormalities in some of the key enzymes involved in the metabolism of homocysteine, and folic acid deficiency is the most important cause of elevated serum homocysteine levels in China. Patients with elevated serum homocysteine, especially those with elevated homocysteine associated with hypertension, have a significantly increased risk of future cerebrovascular accidents. Therefore, for patients with hypertension accompanied by elevated homocysteine, in addition to active antihypertensive treatment, small doses of folic acid should be given orally for a long period of time to reduce the risk of future cerebrovascular accidents.