Abstract: OBJECTIVE To evaluate the effect of dexmedetomidine on patients receiving cerebral functional area operation during wake-up test performed under propofol combined with sufentani anesthesial. METHODS Forty ASA physical status Ⅰ or Ⅱ patients,undergoing cerebral functional area operation, requring wake-up test, aged 18?65 years old, weighing 50?70 kg, were randomly divided into control group and dexmedetomidine group with 20 cases in each one. Dexmedetomidine (1 μg?kg^-1) was infused over 10 min before anesthesia induction in dexmedetomidine group; meanwhile, control gorup received an equal volume of normal saline. Anesthesia was induced with target-controlled(TCI) infusion of propofol and sufentanil and cisatracurium. After endotracheal intubation, dexmedetomidine was infused at 0.4 μg?kg^-1?h^-1. TCI of propofol and sufentanil was used to maintain the anesthesia condition as followed: concentration of propofol in plasma was 3-5 μg?mL^-1 with BIS value from 45 to 55; effect-site target concentration of sufentanil was adjusted at 0.1-0.2 ng?mL^-1. Patients in both groups received scalp nerve block, local infiltration into incision and dura mater during the operation. After the dura was open, propofol was withdrawed and the concentration of sufentanil was decreased to 0.1 ng?mL^-1, and in dexmedetomidine group the infusion rate of dexmedetomidine was decrease to 0.1 μg?kg^-1?h^-1. Anesthesia time and consumption of anesthetics before wake-up test, wake-up time, and development of complications and intraoperative awareness during wake-up test were recorded. RESULTS All patients successfully awaked, patiens in dexmedetomidine group need less consumption of propofol than those in control group(P<0.05); the incidence of hypertension, tachycardia, headache and awareness were significantly decreased in dexmedetomidine group than those in control group(P<0.05); the time to arouse the patients during operation was also significantly shorter in dexmedetomidine group than control group(P<0.05). No significant difference in BIS value was found in dexmedetomidine group. CONCLUSION Dexmedetomidine can reduce wake-up time and raise the quality of wake-up test in patients undergoing cerebral functional area operation under propofol combined with sufentanil anesthesia.