Although anaerobic bacterial meningitis is uncommon, patients subjected to resection of head and neck malignancy appear at special risk. In this article, the authors report on a 72-year-old man in whom meningitis developed after extensive resection of the right sinuses for squamous cell carcinoma; initial treatment consisted of intravenous vancomycin and ceftazidime. Intravenous penicillin G was added after the fortuitous early finding of intracellular cocci in Wright-Giemsa stained cerebral spinal fluid submitted for cell count. Cerebral spinal fluid cultures then grew out a pure culture of Peptostreptococcus magnus. The patient had a complete recovery, without neurologic sequelae, recurrence of malignancy, or evidence of infection. Appropriate handling of cerebral spinal fluid specimens is crucial to ensure the correct diagnosis when anaerobic organisms are suspected.