We report a fatal case of meningoencephalitis due to Listeria monocytogenes. A 74-year old alcoholic man presented with high-grade fever lasting for four days without headache and meningeal signs. Routine blood analysis showed leukocytosis, but serum C-reactive protein (CRP) was not significantly elevated. He developed altered consciousness with focal seizure, and cerebrospinal fluid (CSF) examination showed a minor degree of pleocytosis, elevated protein, and hypoglycorrhachia. Repeated CSF examination four days later showed greater increases in cells and proteins as well as severely decreased glucose level. Bacterial culture from the initial CSF showed a growth of L. monocytogenes. Meningoencephalitis caused by L. monocytogenes may have atypical clinical and laboratory features, and should be listed in the differential diagnosis of immunocompromised or elderly patients presenting with fever of unknown origin associated with altered consciousness.