An early treatment and an adequate antimicrobial chemotherapy are major prognostic factors for bacterial meningitis, brain abscesses and related infections. The necessity of an early therapy requires to begin an empiric antibiotic treatment prior to obtain microbiological results. The principles that apply to empiric therapy of other types of infections are equally applicable to the treatment of central nervous system (CNS) infections and include: the capacity of achieving adequate levels of antibiotic in the CNS and for the brain (pharmacokinetic criteria), the knowledge of the most likely etiologic agents for central nervous system infections and their antibiotic susceptibility (bacteriological criteria). The main clinical types of CNS infection are reviewed for their usual etiologic agents, with a definition of an optimal "bacteriological deal" for each situation. Most studies emphasize the striking differences in the clinical features, etiologic agents and prognosis of spontaneously occurring (primary) meningitis, as opposed to post-traumatic or post-surgical, frequently Gram negative bacillary (secondary) meningitis and other CNS infections (brain abscesses and related infections). These studies, as our experience, suggest that the selection of an empiric therapy must be adapted for each clinical situation. Ampicillin still appears to be an ideal agent for empiric therapy for primary meningitis in older children and adults, in whom meningitis are usually caused by N. meningitidis and S. pneumoniae. In younger children (before 6 years), H. influenzae is more often implicated and the occurrence of beta lactamase mediated resistance to ampicillin in as high as 15% of isolates led to use a third generation cephalosporin as an empiric therapy. Neonatal meningitis, meningitis following trauma or surgery, brain abscess, subdural empyema, epidural abscess are caused by various etiologic agents including Streptococcus sp, Staphylococcus sp, Enterobacteriaceae, and for brain infections, anaerobic bacteria. Each situation led to specific recommendations by authors. Finally, miscellaneous aspects of therapy as the usefulness of intrathecal or intraventricular therapy, duration of treatment and place of the neuro-surgery during CNS infections are briefly reviewed.