This HCUP Statistical Brief presents statistics on inpatient stays and treat-and-release ED visits (i.e., those that do not result in admission to the same hospital) with an influenza diagnosis from the 2006–2007 flu season through the 2015–2016 flu season using the 2006–2016 National (Nationwide) Inpatient Sample (NIS) and Nationwide Emergency Department Sample (NEDS). Flu seasons were defined as the 12-month period from August through July of the next year, except for 2015–2016. The 2015–2016 flu season was defined as the 12-month period from October 2015 through September 2016 because of the transition of the International Classification of Diseases coding system from the ninth to the tenth revision in October 2015. Because the 2015–2016 flu season started later than most years, this definition captured most cases.