Patients who experience awareness under surgery may suffer from the post-traumatic stress disorder (PTSD) with its long-lasting psychological damage. In addition, there are also media attention and legal consequences. In spite of understanding its causes, it is still occurring worldwide. This prospective study was conducted to determine the incidence of awareness using the bispectral index monitor (BIS) when its causes are eliminated. There were 2328 patients admitted to the study. Their ages ranged from 14-104 yr (mean 38.6 yr). All patients were interviewed in the postoperative period. There was no report of awareness during the course of surgery. Pre-and intraoperative anesthetic attention to patients presented for surgery, together with the use of modern anesthetic delivery units possessing facilities for monitoring BIS, and anesthetic gases, and the provision of good analgesia, are the most important combination in eliminating awareness during surgery.