This Healthcare Cost and Utilization Project (HCUP) Statistical Brief presents statistics on major ambulatory surgeries performed in hospital-owned facilities using weighted estimates from the 2019 Nationwide Ambulatory Surgery Sample (NASS). Major ambulatory surgeries are defined as select invasive, therapeutic surgical procedures that typically require the use of an operating room and regional anesthesia, general anesthesia, or sedation (i.e., surgeries flagged as “narrow” in the HCUP Surgery Flags Software3). Procedures intended primarily for diagnostic purposes are excluded.