The aim of this study was to assess the effects of meningitis treatment on the serum and cerebrospinal-fluid oxidant and antioxidant status in children with bacterial meningitis. Forty children with bacterial meningitis, at ages ranging from 4 months to 12 years (mean age, 4 years), were enrolled in the study. Within 8 hours after admission (before treatment) and 10 days after clinical and laboratory indications of recovery (after treatment), cerebrospinal fluid and venous blood were collected. Thirty-seven healthy children (mean age, 4 years) were enrolled as control subjects, and only venous blood was collected. Serum total oxidant status, lipid hydroperoxide, oxidative stress index, uric acid, albumin, and ceruloplasmin levels were lower in the patient group after treatment (P < 0.05). Serum total antioxidant capacity levels, vitamin C, total bilirubin, and catalase concentrations were not significantly altered by treatment (P > 0.05). However, cerebrospinal fluid total oxidant status, lipid hydroperoxide, and oxidative stress index levels were higher, and cerebrospinal fluid total antioxidant capacity levels were lower after treatment than before treatment (P < 0.05). In conclusion, we demonstrated that serum oxidative stress was lower, and cerebrospinal fluid oxidative stress was higher, after rather than before treatment in children with bacterial meningitis. (c) 2007 by Elsevier Inc. All rights reserved.