Objective To evaluate the diagnostic value of serum neuron specific enolase(NSE) dynamic changes in brain death patients.Methods After onset of brain death,the serum NSE levels at 24,48 and 72 hours were determined by enzyme linked immunosorbent assay(ELISA) in 30 such patients(brain death group),and the NSE levels were also determined by the same method in 30 extra severe craniocerebral injury patients(cerebral injury group)as concurrent control for comparisons.Results The serum NSE level increased over time both in brain death and severe craniocerebral injury patients.The serum NSE levels of brain death patients were higher than those in extra severe craniocerebral injury patients significantly at 24,48 and 72 hours after onset respectively(all P370 ?g/L) in 5 days,and 3 cases in 7 days.But similar phenomenon was not observed in 13 cases with severe craniocerebral injury and having stayed in ICU over 1 week whose serum NSE level,on the contrary,was decreased gradually after 3 days of onset. It was statistical significant when the serum NSE levels were compared at the same time points between the two groups(P