A 6-year-old girl, operated upon for an optic nerve astrocytoma (resection limited to the intraorbital portion of the nerve), developed 3 years later symptoms and signs of chiasmatic invasion. Nine years after surgery (1980), she suffered from pneumococcal meningitis, due to cerebrospinal rhinorrhea that had been present in the last few years. A repeated neuroradiological investigation showed the site of the fistula and cerebral ventricles of normal size. The case is argued for bulb-to-chiasm resection of an optic nerve glioma: a spontaneous cerebrospinal rhinorrhea with its potential dangers of meningitis seems to be one more complication of a limited resection of these tumors. It is felt that this is an unusual instance of spontaneous rhinorrhea from direct tumoral erosion. The diagnostic value of metrizamide cisternography for the assessment of presence and site of the fistulous leak is confirmed.