PURPOSE: A clinical diagnosis of meningitis is difficult because of the paucity of physical findings in children. Not all of the meningitis patients show nuchal rigidity, Kernig's sign or Brudzinski's sign. Lumbar punctures were done because of unexplained fever, changes in behavioral or mental status, seizures or skin petechiae in febrile patients. But sometimes cerebrospinal fluid(CSF) findings are not compatible with menigitis for those whose clinical symptoms indicate menigitis. Pediatricians are frequently confronted to the problem of a sick child whose CSF has no white blood cells but the child has a meningeal irritation sign. Therefore, the levels of CSF beta2 microglobulin from children with positive meinigeal irritation signs were examined to evaluate the diagnosis of meinigitis. METHODS: From March to August 2002, We examined the levels of CSF beta2 microglobulin from children with positive meningeal irritation signs by competitive radioimmunoassay in 35 suspected meingitis patients and 12 control patients in the Department of Pediatrics of Chungnam National University Hospital. RESULTS: In 35 suspected menigitis patients, 20 patients were diagnosed as meningitis and 15 patients were no evidence of meningitis in their CSF findings. In the WBC counts of the CSF, meinigitis patients had 268/mm3 and meningismus patient had 2.3/ mm3 on average. In the levels of the CSF beta2 microglobulin concentrations, the two groups were not different. For the 20 meningitis patiens, the average value was 0.193+/-0.054 while it was 0.169+/-0.028 for the 15 meningismus patients and 0.102+/-0.021 for the 12 control patients(P<0.05, <0.05, P>0.05) CONCLUSION: These data demonstrate that the meningeal irritation sign is a meaningful sign for meningitis but the initial CSF findings do not always confirm the diagnosis. So, if patients have a meningeal irritation sign, the patient should be carefully examined and additional diagnostic tools such as the CSF beta2 microglobulin concentration can be used.