The initiation of antibiotic treatment on suspicion of bacterial meningitis is important, but it is not enough to improve the prognosis for patients, especially those with pneumococcal meningitis. The mortality and morbidity of pneumococcal meningitis are still devastating, and results of a recent randomised trial have shown evidence in favour of dexamethasone treatment given before or with the first antibiotic dose. Adjuvant dexamethasone is unequivocally recommended in children and adults with haemophilus meningitis or pneumococcal meningitis. The benefit of adjunctive dexamethasone is likely to be greatest in patients who are otherwise healthy and present early with acute bacterial meningitis. Dexamethasone is not currently recommended for the treatment of gram-negative bacillary meningitis and neonatal meningitis. Dexamethasone, before or with the first dose of antibiotic, is likely to be one of the most significant practice changes that will benefit many adults and children with common types of acute bacterial meningitis and has been of proven value in the developed world.