One of the fundamental goals in providing general anesthesia is to render the patient unconscious and oblivious to the events of the surgical procedure. If the anesthetic state becomes inadequate, a patient may regain consciousness and potentially form memories of the intraoperative period. This complication of anesthesia – intraoperative awareness with recall – has been recognized for decades, ... [Show full abstract] and it recently has become the focus of concerted efforts to reduce its frequency. Anesthesia strategies can be developed to minimize the occurrence and consequences of intraoperative awareness.Incidence and etiology Several prospective investigations documented the prevalence of intraoperative awareness with recall at approximately 0.1% to 0.2%; that is, it occurs in one in 500 to 1000 patients undergoing general anesthesia. These incidence measures have used a specific and simple structured interview to determine whether intraoperative memories have been formed. Patient recall of intraoperative events may be delayed; consequently, several interviews during the first 7 days will detect a greater occurrence of awareness. Initial interviews in the postanesthesia care unit likely detect only two-thirds of awareness episodes. The incidence of awareness determined using a patient interview approach may be substantially lower than the frequency of spontaneous patient complaints of awareness. In one survey of a large anesthesia practice, a quality assessment survey detected a much lower incidence of awareness based on patient feedback.