The incidence of complications of endoscopic sinus surgery (ESS) in a combined experience with 2108 total patients is compared to complications in 11 other series of patients (2583 total) who underwent ESS and 6 series of patients (2110 total) who underwent traditional endonasal sinus surgery. The incidence of major perioperative complications was 0.85%, with cerebrospinal fluid (CSF) leak being the most common. The most common minor complications of ESS were those related to orbital penetration and middle turbinate adhesions; minor complications occurred in 6.9% of the 2108 patients. There were no statistically significant differences in the overall incidences of major complications between this series and the other two groups. Recommendations are made for the prevention of complications during ESS.