Pathology of the frontal sinus represents one of the most challenging and technically demanding areas for the sinus surgeon to reach endoscopically. Cerebrospinal fluid (CSF) leaks in other parts of the sinonasal cavity have been repaired with relatively high success rates using accepted endoscopic techniques for nearly 20 years , yet little has been published regarding repair of frontal sinus defects. The use of 70° endoscopes and giraffe instruments allows excellent access to the frontal recess, but postoperative stenosis, anatomic variants, and CSF leaks associated with the posterior table can make repair of these defects very challenging and pushes the limits of endoscopic repairs. Pertinent frontal sinus anatomy, etiologies of CSF leaks, preoperative imaging and considerations, and the technique and type of repair will be discussed. © Springer-Verlag Berlin Heidelberg 2005.