A review of the literature on primary diffuse meningeal gliomatosis (DMG) yielded three cases and we report a fourth. DMG is a syndrome characterized by extensive basal and spinal chronic meningitis with mental confusion, headaches, diplopia, papilledema and cranial nerve palsies. The cerebrospinal fluid (CSF) has a markedly elevated protein content, moderate mononuclear pleocytosis and a normal or low glucose. This picture invariably leads to the diagnosis and treatment of tuberculous or fungal meningitis despite persistently negative cerebrospinal fluid (CSF) cultures. Reaction of exfoliated CSF cells with glial fibrillary acidic protein (GFAP) immunoperoxidase labelled antibody is suggested as a diagnostic tool. A basal meningeal biopsy appears to be the only alternative diagnostic approach.