Cerebrospinal fluid (CSF) leakage may cause immediate or delayed complications, such as ascending meningitis and brain abscess, potentially lethal complications that may appear years or decades after the trauma. Thus, the initial treatment of a CSF fistula may decisively influence long-term outcome. In a retrospective study including 1036 consecutive patients presenting with severe cranial trauma from May 1990 to March 1996, we identified 27 patients (2.6%) with CSF fistulas. Patients with a post-traumatic CSF leak were most commonly males between 15 and 40 years involved in a motor vehicle accident. The most common sites of injury were the frontal area and anterior skull base for those patients with rhinorrhea and the temporal bone for those patients with otorrhea. A transcranial repair was used for large cranial base defects (n = 10), while conservative treatment, comprised of bedrest, lumbar drainage, and medications, was used for smaller fistulas (n = 17). Four patients (40%) initially treated with a transcranial repair, and five patients (29%) initially treated conservatively, developed a meningitis. Therefore, neither the conservative approach nor the transcranial repair was able to prevent this considerable incidence of ascending meningitis. We believe that the high incidence of meningitis is not acceptable; thus, we are now evaluating early intervention using endoscopic techniques for the identification and/or repair of post-traumatic fistulas.