Background : This study was designed to evaluate the effect of propofol and oral clonidine on bleeding and their efficacy in blunting the hemodynamic effects of epinephrine during endoscopic sinus surgery. Methods : Informed consent was obtained from eighty patients scheduled for endoscopic sinus surgery under general anesthesia. All patients received atropine 0.5 ㎎ IM for premedication. Group I (n = 20) received thiopental sodium 5 ㎎/㎏ and vecuronium 0.1 ㎎/㎏ followed by an isoflurane 1-1.5 vol% in O_2/N_2O 50/50. Group P (n = 20) received propofol 2 ㎎/㎏ and vecuronium 0.1 ㎎/㎏ followed by an infusion of 6-10 ㎎/㎏/hour in O_2/N_2O 40/60. Group P + 75 (n = 20) received oral clonidine 75 ㎍ and Group P + 150 (n = 20) received oral clonidine 150 ㎍ 60 min bofore induction of anesthesia. In anesthetic induction and maintenance, Group P + 75 and Group P + 150 were identical to Group P. Blood pressure, heart rate, EKG and SpO_2 were continuously monitored. Blood losses were collected and measured at the end of each procedure. Pre- and postoperative hematocrit were checked. The duration of heart rate to peaked level and side effects were observed in all patients after the intranasal injection of epinephrine. Results : The average estimated blood losses in Group P, P + 75 and P + 150 were significantly less than that of Group I (P < 0.05). In Group P + 150, the duration of heart rate increase was significantly shorter than that of Group I (P < 0.05). In Group P + 150, mean arterial pressure and the difference between preoperative and postoperative hematocrit were significantly less than that of Group I (P < 0.05). Conclusions : General anesthesia based on propofol infusion may have the advantage of decreased bleeding compared with conventional inhalation agents during endoscopic sinus surgery. Tachycardia in response to intranasal epinephrine injection was attenuated by oral clonidine. (Korean J Anesthesiol 2002; 42: 23~30)