Abstract： Objective To evaluate the effect of controlled hypotension in functional endoscopic sinus surgery with Labetalol. Methods Totally 50 patients(ASAⅠ～Ⅱ class aged 20 ～65 yr weighing 42 ～ 80 kg)were scheduled for functional endoscopic sinus surgery(FESS)and were randomly divided into two groups.All patients had endotracheal intubation inhalation compound venous anesthesia.Patients in control group hadn't accepted controlled hypotension.Patients in labetalol group accepted intravenous injection of labetalol,which makes their mean atrial pressure(MAP)decreased about 25%.All patients' electrocardiograph,heart rate and MAP were monitored.Awake time of each patient was recorded.Heart rate and MAP at T0(preanethesia),T1(30 minutes after initiation of controlled hypotension)and T2(20 minutes after the end of controlled hypotension)were recorded and analyzed. Results MAP of the patients in Group B can be reduced according to the needs of target(P ＜ 0.01).The operation time and bleeding volume were less than the patients in group A(P ＜ 0.05),but the recovery time after surgery had no significant difference between the two groups(P ＞ 0.05). Conclusion It is safe and effective to use controlled hypotension in endoscopic sinus surgery with Labetalol and it can significantly reduce blood loss and operative time.