Aim To investigate the relationship between the risk of cerebral infarction and plasma homocysteine levels. Methods Levels of plasma homocysteine, serum folic acid and vitamin B12 of 200 patients with acute cerebral infarction and 100 healthy subjects were determined. Results The mean plasma homocysteine was significantly higher in the cerebral infarction group (18.54±6.28 μmol/L) compared with that in the control group (10.35±3.64 μmol/L, p<0.001). The mean serum folic acid and vitamin B12 were significantly lower in the cerebral infarction group (4.62±2.48 μg/L and 246.4±86.2 ng/L) compared with those in the control group (8.36±1.58 μg/L and 348.3±58.4 ng/L, p<0.001). Conditional logistic procedure analysis showed that plasma homocysteine was independent risky factor of cerebral infarction. Correlation coefficients between log plasma homocysteine level and serum folic acid, vitamin B12 indicated an inverse correlation (r=-0.448, p<0.001; r=-0.264, p<0.01, respectively). Plasma homocysteine was negatively correlated with the European stroke scale score (r=-0.684,p<0.001). Conclusions Hyperhomocysteinemia increase the risk of cerebral infarction. It can aggravate the pathogenetic condition of cerebral infarction too.