Four-day dexamethasone therapy has been used to treat bacterial meningitis. This prospective, randomized study compared the effect of a 2-day versus a 4-day regimen. Children (n = 118, ages 2.5 months to 15 years) were evaluated; 50% of the cases were due to Neisseria meningitidis and 40% to Haemophilus influenzae type b. Patients were treated intravenously (iv) mainly with conventional antimicrobial therapy and were randomly assigned to receive dexamethasone, 0.15 mg/kg iv every 6 h for 2 or 4 days. The clinical response was similar for both dexamethasone regimens. The meningococcal meningitis patients survived without neurologic or audiologic sequelae. On long-term follow-up, neurologic sequelae or moderate or more severe unilateral or bilateral hearing impairment (or both) were found in 1.8% and 3.8% of patients treated with dexamethasone for 2 and 4 days, respectively. The 2-day regimen appears appropriate for the treatment of H. influenzae and meningococcal meningitis.