The authors review 23 cases of hospital-acquired meningitis occurring over a 15 year period in neurosurgical patients. Factors associated with the development of meningitis include recent craniotomy, cerebrospinal fluid leak, the presence of ventricular or lumbar drainage tubes, and skull fracture. Four cases were caused by Staphylococcus epidermidis; one of these patients died. In 19 cases, Gram-negative enteric bacteria were the etiologic agents, most commonly members of the Klebsiella-Enterobacter-Serratia group. Eleven of these patients died. The particular antibiotic or group of antibiotics used and the route of administration made no difference in the outcome of Gram-negative bacillary meningitis.