Interleukin (IL)-8 concentrations were analyzed in 70 cerebrospinal fluid (CSF) samples from patients with meningitis of different etiologies and in 34 normal CSF samples. Patient groups included those with pyogenic meningitis, viral meningitis, self-resolving aseptic meningitis without a specific diagnosis, and meningitis of other etiologies and normal CSF from patients with and without neurologic disease. All samples from patients with pyogenic meningitis (18) but only 3 from patients with meningitis of other etiologies and with CSF polymorphonuclear leukocyte (PMNL) counts > or = 80% had IL-8 levels > or = 2.5 ng/mL. IL-8 was above the normal level (< or = 0.5 ng/mL) in samples from 5 of 13 viral and 8 of 23 self-resolving aseptic meningitis patients and in 7 of 13 samples from patients with meningitis caused by other microorganisms. There was a significant relationship between IL-8 levels and CSF PMNL counts in patients with nonpyogenic meningitis. The data suggest a possible role of IL-8 as PMNL chemotactic factor in different infections of the subarachnoid space, not only in pyogenic meningitis.