Routine use of steroids as adjunctive treatment of bacterial meningitis remains controversial. We have carried out a prospective, placebo-controlled, double-blind study of dexamethasone in 115 children with acute bacterial meningitis in Switzerland. The patients were randomly assigned to receive either placebo (n = 55) or dexamethasone (n = 60) in addition to optimum antibiotic treatment (100 mg/kg daily ceftriaxone). Dexamethasone therapy (0.4 mg/kg) was started 10 min before the first dose of ceftriaxone and given every 12 h for 2 days. Baseline demographic, clinical, and laboratory features of the two groups were similar. After 24 h treatment meningeal inflammation as shown by cerebrospinal fluid (CSF) glucose concentration was significantly less with dexamethasone than with placebo (mean increase in glucose 63 [76] vs 40 [75]%, p = 0.008). However, other indices of inflammation showed similar changes in both groups. Addition of dexamethasone did not affect the rate at which CSF became sterile. Both groups showed prompt clinical responses and similar frequencies of complications (15 vs 12%). Monitoring for possible adverse effects of dexamethasone revealed no abnormalities. At follow-up examinations 3, 9, and 15 months after hospital discharge, 9 (16%) of 55 placebo recipients and 3 (5%) of 60 dexamethasone recipients had one or more neurological or audiological sequelae (p = 0.066); the relative risk of sequelae was 3.27 (95% CI 0.93-11.47). Our results and those of similarly designed studies lead us to believe that adjunctive dexamethasone therapy improves outcome from bacterial meningitis in infants and children. We recommend its use, preferably in the dose regimen used in this study.