PURPOSE: Interleukin(IL)-10 is an antiinflammatory cytokine produced by monocytes/macrophages. Granulocyte colony-stimulating factor(G-CSF) plays an important role, not only as a hemopoietic factor but also as a regulating factor for a biologic defense system by neutrophils, in the foci of infection. We studied G-CSF and IL-10 levels in the serum and cerebrospinal fluid(CSF) of patients with aseptic meningitis and investigated the relationship of G-CSF and IL-10 with other inflammatory cells. METHODS: We measured IL-10 and G-CSF levels in the serum and CSF of children with or without aseptic meningitis using ELISA and compared them with other inflammatory cells in the CSF. RESULTS: CSF levels of IL-10 & G-CSF on admission were significantly higher in the aseptic meningitis group than in the control group. IL-10 and G-CSF levels in the CSF were higher than those in the serum(P<0.001). Mean CSF IL-10 & G-CSF levels during the recovery stage decreased significantly compared to those of the symptomatic stage(P<0.001). Significant correlations were found between CSF IL-10 levels and mononuclear cell counts(r=0.26, P<0.05), and between G-CSF levels and neutrophil counts in the CSF(r=0.44, P<0.005). CSF levels of G-CSF were highest on the 1st day of the illness, although CSF IL-10 levels reached its peak on the 3rd day of the illness. CONCLUSION: IL-10 and G-CSF are produced in the CSF of patients with aseptic meningitis and may play an immunoregulatory role by recruiting inflammatory cells from the peripheral blood at the initial stage of aseptic meningitis.