Purpose : Aseptic meningitis is an infection of CNS caused by virus and there are remarka-ble changes in endogenous cytokine level. Interleukin-6 is a pleiotropic and multi-functional cyt-okine and plays a central role in host defense mechanisms. We studied the IL--6 level in serum and CSF with the patients of aseptic meningitis and investigated the relationship of IL-6 with C RP and other laboratory data. Methods : The spinal tap was done twice, each at the acute and subacute stage. The subje-cts consisted of 20 patients with aseptic meningitis who were admitted to Jang-Song Hospital fr om June to July, 1993. All the sera were stored in deep freezer at-20℃ until use. The IL-6 lev-el was measured by sandwich ELISA method and the CRP level by fluorescence polarization immunoassay. Results : In aseptic meningitis, there was significant increase of IL-6 in both serum and CSF and it also had a good correlation with CRP and fever duration. The WBC count and protein co-ncentration were not reliable for clinical manifestation. Conclusion : These results suggest that interleukin-6 level can be a reliable index of infla-mmation in CNS in aseptic meningitis and the IL-6 may be producted not only by WBC but also by other cells in CNS.