Endoscopic sinus surgery is one of the most common surgical procedures in otolaryngology. However, the location of the orbit and intracranial contents in close proximity to the paranasal sinuses makes endoscopic sinus surgery potentially hazardous. Otolaryngologists have employed computer-aided surgery, or image-guided surgery, over the past two decades to enhance surgeon confidence, allow more thorough surgical dissections and possibly reduce the complication rate of endoscopic sinus surgery. Computer-aided surgery utilizes preoperative imaging to provide real-time localization of surgical instruments in the surgical field. Although computer-aided surgery originated in the neurosurgical realm, otolaryngologists soon appreciated that this technology could assist in identifying critical orbital or intracranial structures surrounding the paranasal sinuses, and potentially aid in decreasing complications. In this article, the history of image-guidance systems and their application to surgery of the paranasal sinuses and skull base will be reviewed. The components of computer-aided surgery systems and the currently available technologies for surgical instrument tracking are discussed, as well as the advantages and disadvantages of each of the tracking technologies. In addition, issues relating to the accuracy of image-guidance systems are examined. A number of institutional series noting surgeon experience with computer-aided surgery in the domain of paranasal sinus surgery are reviewed. Furthermore, the authors evaluate the utility of image-guidance technology beyond the paranasal sinuses and skull base, such as its use in surgery of the pituitary gland and pterygopalatine fossa, research and resident education. Finally, potential future applications of computer-aided surgery technology are discussed.