Our aim in this work is to define the importance of anatomical knowledge in septoplasty operation and to prevent complications. Septoplasty is one of the most common operations in otorhinolaryngology to treat the nasal obstruction caused by septal deviation. During and after septoplasty, there are some recorded complications, such as hemorrhage, hematoma, septal abscess, septal perforation, saddle nose, infection, anosmia, visual disturbances, cavernous sinus thrombosis, meningitis, pneumoencephalos, subarachnoid hemorrhage, subdural empyma, brain abscess, periorbital emphysema, toxic shock syndrome, and cerebrospinal fluid (CSF) rhinorrhea. Some of the complications are rare, but their results are life threatening. We report a rare complication of septoplasty CSF rhinorrhea. Two consecutive cases of CSF fistulas after septoplasty operation are presented. Both of the cases were treated endoscopically. The possible mechanisms and different treatment options are discussed. Prevention of the CSF fistula in septoplasty is more important than its treatment. Realizing the anatomic variations and gentle manipulation at the ethmoid roof is essential. (C) 2004 Elsevier Inc. All rights reserved.