Cerebrospinal fluid rhinorrhea is an uncommon but dangerous disease. Many lethal complications, such as bacterial meningitis and pneumoencephalus, may be the result of cerebrospinal fluid rhinorrhea. Otolaryngologist, neurosurgeons and radiologists must know how to diagnose, how to localize the site of leakage and how to choose the best method of treatment. A case of cerebrospinal fluid rhinorrhea and meningitis due to improper sinus surgery is presented. Satisfactory result, such as avoidance of unnecessary brain tissue damage, can be obtained by extracranial endonasal repairing of the fistula with a composite septal flap.