Antimicrobial agents for the treatment of bacterial meningitis and other pyogenic intracranial infections have now been in use for approximately 45 years. The last decade, however, has been a period of tremendous advances in knowledge of the pharmacokinetics and other characteristics of the available drugs. The identification of factors that affect their in vivo metabolism and excretion, the importance of drug interactions, and the development of methods for estimation of serum and cerebrospinal fluid levels have added both complexity and sophistication to the clinical utilization of the antimicrobial agents. The number of available antimicrobials has expanded greatly during recent years, although the penicillins, chloramphenicol, and the aminoglycosides remain the mainstay of antibiotic treatment in the majority of cases of bacterial infection of the central nervous system.