A previously healthy man developed a progressive neurologic illness characterized by an "aseptic meningitis syndrome," progressive hypoglycorrhachia, and severe brain-stem dysfunction. Initial dramatic response to antituberculosis therapy supported the diagnosis of tuberculous basilar meningitis; however, Listeria monocytogenes eventually grew in a blood culture, and the patient recovered following intravenous ampicillin therapy. The entity of listerial rhombencephalitis should be considered as a treatable cause of acute, progressive brain-stem meningoencephalitis.