We reviewed 135 cases of acute community-acquired bacterial meningitis at a municipal teaching hospital during a six-year period, with special emphasis on promptness of initial antimicrobial therapy. Overall mortality was 5% for the 121 childhood cases, compared to 43% for the 14 adult cases (P less than .001). The mean duration between arrival in the emergency department and the administration of appropriate antibiotics was 2.1 hours for the pediatric cases, compared to 4.9 hours for the adult cases (P less than .02). Factors that may contribute to delays in institution of appropriate antimicrobial therapy for adult patients with meningitis include the relative infrequency of this condition, the presence of concomitant disease processes, and the frequent practice of obtaining a computed tomography scan prior to performing lumbar puncture. Prompt institution of antimicrobial therapy for acute meningitis, especially for adult pneumococcal meningitis, remains a major challenge for emergency physicians.