We used a large database of prospectively collected data on pediatric sedation/anesthesia outside the operating room provided by a wide range of pediatric specialists to delineate the nature and frequency of adverse events associated with propofol-based sedation/anesthesia care. Data were collected by the Pediatric Sedation Research Consortium, a collaborative group of institutions dedicated to improving sedation/anesthesia care for children internationally. Members prospectively enrolled consecutive patients receiving sedation or sedation/anesthesia for procedures. The primary inclusion criterion was the need for some form of sedation/anesthesia to perform a diagnostic or therapeutic procedure outside the operating room. There were no exclusion criteria. Data on demographics, primary illness, coexisting illness, procedure performed, medications used, procedure and recovery times, medication doses outcomes of anesthesia, airway interventions and adverse events were collected and reported using web-based data collection tool. For this study, we evaluated all instances where propofol was used as the primary drug in the sedation/anesthesia technique. Thirty-seven locations submitted data on 49,836 propofol sedation/anesthesia encounters during the study period from July 1, 2004 until September 1, 2007. There were no deaths. Cardiopulmonary resuscitation was required twice. Aspiration during sedation/anesthesia occurred four times. Less serious events were more common with O(2) desaturation below 90% for more than 30 s, occurring 154 times per 10,000 sedation/anesthesia administrations. Central apnea or airway obstruction occurred 575 times per 10,000 sedation/anesthesia administrations. Stridor, laryngospasm, excessive secretions, and vomiting had frequencies of 50, 96, 341, and 49 per 10,000 encounters, respectively. Unexpected admissions (increases in levels of care required) occurred at a rate of 7.1 per 10,000 encounters. In an unadjusted analysis, the rate of pulmonary adverse events was not different for anesthesiologists versus other providers. We report the largest series of pediatric propofol sedation/anesthesia for procedures outside the operating room. The data indicate that propofol sedation/anesthesia is unlikely to yield serious adverse outcomes in a collection of institutions with highly motivated and organized sedation/anesthesia services. However, the safety of this practice is dependent on a system's ability to manage less serious events. We propose that our data suggest variables for training and credentialing providers of propofol sedation/anesthesia and the system characteristics that promote safe use of this drug.