Background & Aims: Propofol is an effective sedative in advanced endoscopy. However, the incidence of sedation-related complications is unclear. We sought to define the frequency of sedation-related adverse events, particularly the rate of airway modifications (AMs), with propofol use during advanced endoscopy. We also evaluated independent predictors of AMs. Methods: Patients undergoing sedation with propofol for advanced endoscopic procedures, including endoscopic retrograde cholangiopancreatography, endoscopic ultrasound, and small-bowel enteroscopy, were studied prospectively. Sedative dosing was determined by a certified registered nurse anesthetist with the goal of achieving deep sedation. Sedation-related complications included AMs, hypoxemia (pulse oximetry [SpO2] < 90%), hypotension requiring vasopressors, and early procedure termination. AMs were defined as chin lift, modified face mask ventilation, and nasal airway. We performed a regression analysis to compare characteristics of patients requiring AMs (AM+) with those who did not (AM-). Results: A total of 799 patients were enrolled over 7 months. Procedures included endoscopic ultrasound (423), endoscopic retrograde cholangiopancreatography (336), and small-bowel enteroscopy (40). A total of 87.2% of patients showed no response to endoscopic intubation. Hypoxemia occurred in 12.8%, hypotension in 0.5%, and premature termination in 0.6% of the patients. No patients required bag-mask ventilation or endotracheal intubation. There were 154 AMs performed in 115 (14.4%) patients, including chin lift (12.1%), modified face mask ventilation (3.6%), and nasal airway (3.5%). Body mass index, male sex, and American Society of Anesthesiologists class of 3 or higher were independent predictors of AMs. Conclusions: Propofol can be used safely for advanced endoscopic procedures when administered by a trained professional. Independent predictors of AMs included male sex, American Society of Anesthesiologists class of 3 or higher, and increased body mass index.