Neuron-specific enolase (NSE) levels of cerebrospinal fluid (CSF) were measured in 39 patients with ischemic stroke and 15 controls. There was a significant increase of CSF NSE in patients with acute ischemic stroke as compared with the controls. The altered CSF NSE levels were well correlated with the infarct size in CT scan. The CSF NSE levels were higher in 6-patients who were diagnosed as multi-infarct dementia (MID) after 6-month follow-up than in 22 non-MID patients of this series. Our research supports the view that CSF NSE can be a useful biochemical marker for brain ischemia. The importance of CSF NSE for dementia related to ischemic stroke is worth further studying.