PURPOSE: This study was launched to classify subjects of the CSF examination and improve early diagnosis of meningitis and its treatment in children who have had a first febrile seizure. METHODS: From March 1995 to September 2003, children aged 3 months to 5 years who had had treatment for febrile seizure were analyzed as to their age at first seizure, type of seizure, CSF examination, and prevalence of meningitis. RESULTS:The largest age group distribution among the 780 children was 356(45.6%) children who were under 18 months. One hundred ninteen(15.3%) patients received the CSF examination, and out of those 68(19.1%) were less than 18 months old. Twenty five(3.2%) children were diagnosed with meningitis; those less than 18 months old were 15(4.2%). Two(0.2%) were diagnosed as bacterial meningitis. Out of 780 patients 599(76.8%) were simple febrile seizure patients. Out of 32(5.3%) who received the CSF examination, nine were diagnosed as meningitis. In complex febrile seizure, 86(52.1 %) out of 165(21.2%) received CSF examinations and 16(9.7%) of those were diagnosed as meningitis. Thus, there was a higher prevalence of meningitis in children presenting complex febrile seizure. CONCLUSION: To diagnose meningitis with the CSF examination in the first febrile seizure, the patient's general condition, such as clinical symptoms and types of seizure, are more important than the ages of the patients. We suggest that experienced physicians should be concerned with doing an early diagnosis of meningitis and thus reduce the number of CSF examinations of children with febrile seizures.