The in vitro activity of meropenem was compared with those of penicillin, ampicillin, cefuroxime, cetriaxone, cefotaxime, rifampicin, chloramphenicol, sulphadiazine and ciprofloxacin against 121 British meningococcal isolates by a microdilution method in Mueller-Hinton broth and by the E test. All meningococcal strains were susceptible to the agents except for ampicillin (88.4%), penicillin (88.4%), sulphadiazine (57.9%) and rifampicin (95%). The emergence of resistance problems among meningococcal isolates stresses the need for their constant monitoring and of the development of new agents. In this study we have shown that meropenem is highly active in vitro against Neisseria meningitidis. Recent studies have indicated that meropenem is highly active clinically and bacteriologically in the treatment of bacterial meningitis. Thus, the potentials of meropenem as meningococcal prophylactic and therapeutic agent needs to be fully evaluated.