ABSTRACT ANESTHETIC ADVERSE EVENTS have been found to occur more frequently in surgical procedures performed after 4 PM. THE MAJOR FACTORS that contribute to increased anesthetic adverse events include fatigue, circadian rhythm lows or dips, and administrative delays. AN INCREASED SHORTAGE of anesthesia care providers is likely to create longer work hours, thus increasing fatigue, which can lead to more anesthetic adverse events. Awareness of and education about adverse events and solutions are imperative. AORN J 88 (July 2008) 79–87. © AORN, Inc, 2008.