Subarachnoid hemorrhage is the most common cause of cerebral salt wasting syndrome. There are few reports of this condition in infectious meningitis. We describe a patient with hyponatremia and bacterial meningitis. Hyponatremia rapidly improved after administration of sodium chloride. The purpose of this report is to alert clinicians to the fact that hyponatremic patients with central nervous system disease do not necessarily have a syndrome of inappropriate secretion of antidiuretic hormone (SIADH), but may have cerebral salt wasting syndrome. By contrast with SIADH, the treatment requires saline administration.