Since its introduction, functional endoscopic sinus surgery (FESS) has demonstrated success rates of 76% to 98%. A small group of the patients in whom initial FESS and optimal medical therapy fail require revision endoscopic sinus surgery (RESS). This group has recently been studied by several authors, and we have evaluated a group of 90 RESS patients selected from 753 consecutive primary FESS patients. Patients were followed for a mean of 22.8 months. Extent of disease, history of polyps, allergy, previous traditional endonasal sinus surgery, male gender, chronic steroid use, and the presence of a deviated septum all appeared to adversely affect RESS outcome. The surgeon's knowledge of the sinus anatomy is critical, especially in revision sinus cases in which landmarks are distorted or absent. In our review, RESS was associated with a 1% major complication rate and was successful in 67% of patients. Computer-assisted endoscopic sinus surgery integrates preoperative imaging with realtime endoscopic visualization, augments the surgeon's knowledge of anatomy, and helps to minimize patient risk.