Viridans streptococcus, an indigenous bacterial species of the mouth and gastrointestinal tract, is thought to be a rare cause of bacterial meningitis. The type of streptococcus involved is important because each type causes a different kind of meningitis and is associated with a different outcome. A 39-year-old previously healthy man was admitted due to the onset of acute purulent meningitis. A cerebrospinal fluid culture grew Streptococcus sanguis (S. sanguis). Although the patient was asymptomatic for dental caries, odontogenic maxillary sinusitis was found to be the cause of the meningitis. Treatment with intravenous antibiotics was successful. Following a review of the pertinent literature, we discuss the characteristics of S. sanguis meningitis.