18 patients presenting a circumscribed cerebrospinal fluid (CSF-) leak in the region of the ethmoidal roof, the olfactory cleft or the sphenoidal sinus, were operated on via the endonasal route. Dural laceration could be attributed to paranasal sinus surgery (iatrogenic CSF-leak, N = 11) and to other traumas (N = 6). In one case, no obvious cause was detectable (spontaneous CSF-leak). Using the 70-degree angular optical device, the dural lacerations were closed by autogenous grafts of conchal mucosa with the help of fibrin glue. The average time of postoperative observation was 17 months. No liquorrhoea, meningitis or cerebral abscess was observed postoperatively.