Adenotonsillectomy (AT) is one of the most common surgical procedures performed in children and adults. We aim to assess the factors associated with changes in the incidence of and indications for AT using population-level data.This retrospective cohort study investigated patients who underwent AT between 1997 and 2010 by using data from the Taiwan National Health Insurance Research Database. We examined surgical rates and indications by the calendar year as well as age, sex, hospital level, and insured residence areas for the correlating factors.The average annual incidence rate of AT was 14.7 per 100,000 individuals during 1997-2010. Pediatric (