BACKGROUND: Because the propofol TCI software commands the syringe pump to deliver a rapid infusion at a rate of 1200 ml/hr until the pharmacokinetic model predicts that the selected target concentration has been reached, the hemodynamic changes are predicted. To this change, several methods could be considered and the fentanyl injection is one of them. METHODS: Sixty adult patients scheduled for orthopedic surgery were randomly alldegrees Cated into four groups according to amount of fentanyl injected during induction period(group 1: no fentanyl, group 2: 0.75 microgram/kg, group 3: 1.5 microgram/kg, group 4: 3.0 microgram/kg). Target plasma concentration of propofol was selected as 4.0 microgram/ml and this concentration was achieved using modification of Prys-Roberts method. We evaluated the hemodynamic effect of various doses of fentanyl that injected at Vdpeak effect time and determined the optimal dose of fentanyl during propofol induction using TCI mode. RESULTS: Induction dose(range: 1.25~1.31 mg/kg) of propofol and induction time(range: 46~76 sec) showed no difference among groups. Use of fentanyl was effective for blood pressure stability immediately after intubation, but not effective before and 3 min following intubation. The higher the dosage of fentanyl, the more stable the heart rate. CONCLUSION: It suggest that use of fentanyl for the prevention of abrupt hemodynamic change during propofol induction using target controlled infusion mode is not necessary.