SummaryBetween January 1968 and December 1977, 635 cases of acute bacterial meningitis were admitted to hospitals in the Birmingham Area Health Authority. The epidemiology of these cases was analysed and compared with the 270 cases which were admitted to the regional infectious diseases unit at East Birmingham Hospital (E.B.H.). In children and young adults the meningococcus was the commonest causative organism while over the age of 25 pneumococcal meningitis predominated. AlthoughHaemophilus influenzaewas the second commonest infecting organism it was a rare cause of meningitis in school children and adults, only four cases presenting in these age groups in the Birmingham Area.A detailed analysis was made of the symptoms, signs, laboratory investigations and clinical course of the 270 cases treated at E.B.H.The mortality in the patients with pneumococcal meningitis was 30%. In the meningococcal group it was 3·5% and in the haemophilus groups 7·7%.An analysis of the various treatment regimes employed in the 270 E.B.H. patients supports the view that a single antibiotic is sufficient for the therapy of most forms of bacterial meningitis. Intrathecal antibiotic administration is unnecessary in pyogenic meningitis caused by meningococci, pneumococci orH. influenzae.