ObjectiveTo explore the concentration of the plasma homocysteine (Hcy) and the relationship with TOAST subtypes in patients with acute cerebral infarction. MethodsA total of 120 patients with acute cerebral infarction (ACI) treated from April 2012 to April 2013 were enrolled into the ACI group.They were classified with Korean TOAST classification as five subtypes:atherothrombosis (AT) type,small artery disease (SAD) type,cardioembolism (CE) type,stroke of other disease (SOD) type,and stroke of undetermined etiology (SUE) type.The plasma Hcy concentrations in each group and in 60 heathy people who were selected into the control group were measured.Furthermore,the relationship between plasma Hcy concentration and their subtypes were analyzed. ResultsThe plasma Hcy level in ACI group was significant higher than that in the control group (P<0.01).The levels of plasma Hcy were much higher in patients with AT,SAD,SOD,and CE than those in the control groups (P<0.01).In different subtypes,AT and SAD subtypes had higher homocysteine concentration than SUD and CE subtypes did.The concentration of Hcy in AT and SAD group had no significant difference. ConclusionACI is related to hyperhomocysteinemia.The plasma Hcy level varies with different TOAST subtypes of ACI,specially elevating in the subtypes of AT and SAD,which may indicate that hyperhomocysteinemia may increase stroke risk through proatherogenic effect and endothelial dysfunction.