Sufentanil is a new synthetic opiate analgesic that is 4520 times more potent than morphine in animal experiments. This study evaluated the cardiovascular effects of sufentanil, 15 jig/kg, and air/O2 used as a complete anesthetic with 50% inspired oxygen (air/O2 mixture) in 40 adult patients undergoing elective or emergency cardiac surgery. Statistically significant changes included a decrease in systolic pressure 5 minutes after induction, decreases in systolic and mean blood pressures and peripheral resistance before incision, and a decrease in systolic pressure below control levels 2 minutes after incision. The diastolic pressure increased significantly 5 minutes after sternotomy. Two patients became hypotensive on induction of anesthesia and 16 patients developed hypertension related to sternotomy. These results indicate that sufentanil anesthesia provides good cardiovascular stability for cardiac surgery and is a technique worthy of further evaluation.