Two cases of meningitis due to Listeria monocytogenes in a 73-year-old man and a 77-year-old woman are described. Both patients were admitted to an Emergency Department in acute state, probably caused by cerebral stroke. Neither presented clinical symptoms of meningitis. No other concomitant conditions which might weaken the patient's general state were known to be present. The first patient died after 16 hours, the second after 5. The analysis of the cerebrospinal fluid gave the following information: Case 1: 1,500 cells, 80 percent of which were polynuclear neutrophils; Pandy's reaction was positive; albumin 1.5 g/l and glucose 0.65 g/l. Case 2: 197 cells/mm3, 90 percent of which were polynuclear neutrophils; Pandy's reaction was positive; albumin and glucose were 0.60 and 0.10 g/l respectively. Samples of the cerebrospinal fluid were cultured in various media and pure cultures of Listeria monocytogenes, subtype 4b, were isolated. The source of the infection could not be determined in either of the two cases.