Twenty-one patients who underwent cardiac surgery were assigned to receive high-dose fentanyl rapid sequence anesthesia or conventional high-dose fentanyl anesthesia. In conventional method group, power of delta wave decreased with respect to time. But in rapid sequence group, no decrease was seen until the end of operation. Good maintenance of delta wave in rapid sequence group may be achieved by higher plasma fentanyl concentration and the absence of acute tolerance. In conclusion, high-dose fentanyl rapid sequence anesthesia is a useful method for cardiac surgery.