General anesthesia is a state of drug-induced unconsciousness, during which patients should neither perceive nor recall noxious stimuli. Many patients facing surgery dread the prospect of being awake, in pain and unable to move owing to inadequate general anesthesia. A large multi-center study in the USA showed that, despite modern anesthesia techniques, the overall incidence of awareness or conscious recall remains about 0.1-0.2%. For high-risk (for awareness) surgery, such as cardiac surgery, trauma surgery and obstetric surgery, the incidence of conscious recall approaches 1%. This can lead to extreme anxiety and even posttraumatic stress disorder. Several monitors, including the Bispectral Index (BIS), which is based on processed electroencephalographic information, have been developed in an attempt to monitor depth of anesthesia. A recent landmark study suggested that harnessing the information provided by the BIS monitor decreases the incidence of explicit recall during high-risk surgical procedures from almost 1% to 0.1%. The possible impact of this study is enormous. The American Society of Anesthesiologists and the American Association of Nurse Anesthetists do not currently consider neurological monitors an essential part of routine anesthesia care. Increasingly, members of the anesthetic community are suggesting that for every patient undergoing general anesthesia, especially for procedures where the risk of awareness is considered higher, a neurological monitor, such as the BIS monitor, should be routinely applied.