Three-dimensional computer-aided surgery adds a ‘third-dimension’ to endoscopic sinus surgery. The images it provides have the potential to provide the surgeon with further information that might result in safer and more effective surgery with less surgical morbidity. The gold test, as yet untested, will be whether the technique leads to fewer revision procedures and complications as a result of more complete and safe initial surgery. Its greatest asset lies in reinforcing the surgeons’ estimate of an instrument’s position in a difficult anatomical area. It can augment the learning curve and enhance teaching and training in endoscopic sinus surgery but it is not a substitute for a thorough knowledge of paranasal sinus anatomy.