Aim This study was to clarify whether insulin resistance and hyperinsulinemia are causative factors in the cerebral infarction. Methods Fourtyone consecutive patients with cerebral infarction, who don`t suffer from hypertension, coronary heart disease, diabetes or obesity, were classified into two groups-atherthrombotic infarction (n=25) and lacunar infarction (n=16)-based on clinical findings, brain imaging. Serum insulin, oral glucose tolerance test and lipid analyses were performed. Data were compared with control subjects(n=15). Results After the oral glucose tolerance test, the serum insulin level and the 2 h blood sugar concentration of the atherithrombotic cerebral infarction patients are both higher than those of the contrast group with remarkable statistic significance (P<0.01). The serum insulin level of the lacunar infarction patients is alse higher than that of the contrast group (P<0.05). The levels of serum insulin, insulin/glucose (I/G) were significantly higher in both groups of consecutive patients. Conclusions Insulin resistace and hyperinsulinemia may separately be one of the risk factors for cerebral infarction.