BACKGROUND: The choice of anesthetic agents and adjuvants during outpatient surgery is of critical importance. Propofol is widely used for the induction and maintenance of outpatient anesthesia. Because propofol lacks analgesic properties, very high concentrations may be required when propofol is used as the sole anesthetic drug. Propofol is used with adjuvants such as nitrous oxide or opioid. This study was designed to evaluate the intraoperative hemodynamic response, recovery characteristics and side effects of propofol-fentanyl anesthesia compared with propofol-N2O anesthesia for outpatient surgery. METHODS: Twenty six healthy and unpremedicated patients scheduled for outpatient surgery were randomly allocated to receive either propofol-N2O anesthesia (N-group) or propofol-fentanyl anesthsia (F-group). The patients in N-group were ventilated with nitrous oxide 60~70% in oxygen and the patients in F-group were ventilated with oxygen 40% in nitrogen via laryngeal mask airway (LMA). RESULTS: There was no significant difference in blood pressure during anesthesia, recovery time and side effects between two group. There was significant decrease of heart rate in F-group. CONCLUSION: We concluded that nitrous oxide and fentanyl are reasonable adjuvants of propofol anesthesia in outpatient anesthesia.