BACKGROUND: Febrile seizure (FS) has good prognosis in the majority of cases. But there is an ongoing debate on the relationship between complicated febrile seizure (CFS) and later development of temporal lobe epilepsy (TLE) due to hippocampal sclerosis.OBJECTIVE: To evaluate the level of serum neuron-specific enolase (S-NSE) of children with simple febrile seizure (SFS) and complicated febrile seizure and compare with children with non-FS respiratory tract infection. DESIGN: Contrast observation.SETTING: Department of Pediatrics and Department of Laboratory, Fujian Provincial Hospital. PARTICIPANTS: Forty-nine patients who were admitted to Department of Pediatrics of Fujian Provincial Hospital from June 2002 to September 2003 with FS were enrolled in this study. There were 28 boys and 21 girls aged from 5 to 72 months. All children were divided into 2 groups based on frequency and duration. Thirty-two children whose FS occurred within 24 hours (lasting shorter than single and twice durations and also shorter than 10 minutes) were regarded as SFS group; meanwhile, 17 children whose FS occurred within 24 hours (lasting longer than single and twice durations and also longer than 10 minutes) were regarded as CFS group. Another 23 patients who were admitted to our hospital with respiratory tract infection in the same period, without the history and positive symptoms/features of neurological dysfunction, were enrolled as control group. There were 13 boys and 10 girls aged from 5 months to 86 months. All parents were told the facts. METHODS: 2 mL venous blood was collected from FS children within 24 hours after the seizures. Meanwhile, 2 mL venous blood was also collected from children in the control group. Level of S-NSE was measured with enzyme immunoassay procedure, and differences among groups were compared with t test. MAIN OUTCOME MEASURES: Level of S-NSE in each group. RESULTS: A total of 49 children in FS group and 23 ones in control group were involved in the final analysis without any loss. Levels of S-NSE were (5.17±1.31) μg/L in SFS group, (5.84±1.62) μg/L in CFS group and (4.98±1.51) μg/L in control group, respectively. There were no significant differences among groups (t =0.498- 1.727, P＞ 0.05).CONCLUSION: FS may be not able to cause a severe brain damage.