The authors review their experience with endoscopic repair of skull base defects associated with cerebrospinal fluid (CSF) rhinorrhea and/or encephaloceles involving the paranasal sinuses. Between January 1991 and December 1995, 51 patients were evaluated for anterior and middle cranial fossa defects at a tertiary care facility. Of these patients, 36 underwent endoscopic repair of skull base defects. Factors related to surgical success were analyzed. These factors included etiology, defect location, number of prior attempts at repair, type of graft(s) used, fluorescein use, complications, durations of lumbar drain placement, and duration of CSF leakage prior to repair. During the first attempt, successful endoscopic repair was accomplished in 34 (94.4%) of the 36 patients. The mean duration of follow-up was 24.6 months, with a range of 2 to 57 months. The authors conclude that an endoscopic approach provides a safe and effective means for repairing many skull base defects.