Intraoperative three-dimensional computed tomography (3-D CT) localization has been available for use during functional endoscopic sinus surgery (FESS) for several years, although relatively few otolaryngologists operate in conjunction with this technology. Proponents of intraoperative localization believe that operating with stereotaxis enhances surgical precision and reduces complications. A 1-year review was conducted at the University of Pennsylvania from January 1994 through January 1995. During this period 5% of sinus operations were performed in conjunction with intraoperative localization. The advantages and disadvantages of using intraoperative localization were evaluated for each case. Also examined were type and indication for surgery, anesthesia used, added time, and cost. Overall, intraoperative localization was found to be helpful when anatomy was distorted or obscured. However, selecting patients who may have benefited from localization was often not possible using preoperative data. Ideally, localization should be available for all FESS. Criteria are outlined which will need to be met prior to localization becoming a significant aspect of FESS.