Abstract: Objective: To probe into the relationship between serum homocysteine(Hcy) levels and carotid atherosclerosis in young patients with cerebral infarction.Methods: Forty-four young patients with cerebral infarction were classified into carotid atherosclerosis group and non-carotid atherosclerosis group,and 40 cases with no cerebrovascular dieases acted as controls.The serum Hcy levels were measured by microparticle enzyme immunoassay.Results: The mean serum Hcy level in the patients with cerebral infarction was significantly higher than that in controls(P<0.01),while the mean serum Hcy level in the cerebral infarction group with carotid atherosclerosis was higher than that in non-carotid atherosclerosis group(P<0.05) and the control group(P<0.01).Conclusions: Serum Hcy levels are closely related with carotid atherosclerosis and is an important risk factor for cerebral infarction in young adults.