Bacterial meningitis in adults is fatal in 20% of patients and leads to sequels in 30%. The clinical presentation includes two of the following four symptoms and signs: fever, headache, stiff neck, altered mental status. The essential ancillary test is the analysis of the cerebrospinal fluid. Sometimes, the lumbar puncture is not feasible or deferred (brain computer tomography), requiring antibiotics and corticosteroids early. 80% of bacterial meningitis are secondary to pneumococcus or meningococcus. Empirical antibiotics must be given as soon as possible and provide coverage for these both bacteria. Corticosteroids are also recommended for some meningitis. A score can predict the evolution. Preventive measure must be taken for close contacts of a patient with a meningococcal meningitis.