A 51-year-old man with meningitis due to Klebsiella pneumoniae was treated with cefoperazone 6 to 8 g/day intravenously and was cured. Simultaneous blood and cerebrospinal fluid levels were measured. Trough levels of cefoperazone in cerebrospinal fluid were 9 and 12 mg/L. Cefoperazone should be considered for meningitis due to susceptible organisms resistant to customarily used antibacterial drugs.