Objective To investigate the effect of different doses of dexmedetomidine for conscious blind nasotracheal intubation. Methods Fifty-one ASA?~? patients undergoing general anesthesia for elective surgery were randomly divided into 3 groups.The type of anesthesia for tracheal intubation (n = 17 each ): group ? received surface anesthesia only; group ? and ? received dexmedetomidine 0.5 or 1.0 礸/kg on top of surface anesthesia. All patients received surface anesthesia of nasal cavity, pharynx and larynx, trachea with 1% tetracaine. In group ? and group ? Dexmedetomidine 燞 ydrohloride 營 njection (batch number 10061434, approved number H20090248, produced by Jiangsu HengRui pharmaceutical Co., LTD) was diluted reach to 4 μ g/ml with the 0.9% sodium chloride solution. Then Dexmedetomidine 0.5 or 1.0 礸/kg Ⅳ 15 min. 1 min later conscious blind nasotracheal intubation was operated. MAP, HR and SpO2 were continuously monitored and recorded before anesthesia (T0), before trachea cannula (T1), when tracheal tube was inserted into nasal (T2) and advanced through vocal cords into trachea (T3). Responses like nausea,coughing and restlessness were also recorded. The patient 抯 awareness of the intubation was noted after operation. Results MAP and HR were significantly increased at T2 and T3, compared with them at T0 in group ?(P< 0.05). MAP was significantly decreased at T1, compared with it at T0 (P< 0.05); while MAP and HR were significantly increased at T3, compared with then at T0 in group Ⅱ (P< 0.05).MAP was significantly decreased at T1 、 T2and T3, compared with it at T0 (P< 0.05);and HR was significantly decreased at T1,compared with it at T0 (P< 0.05) in group ?. MAP and HR were significantly increased at T1、 T2 and T3 in group ?, compared with them in group ? and ? (P< 0.01). SpO2 was significantly decreased at T3in group ?,compared with it in group ? and ? (P< 0.01). MAP was significantly decreased at T1 、T2and T3 in group ?,compared with it in group ? (P< 0.05). HR was significantly decreased at T2and T3 in group ? ,compared with it in group ? (P< 0.05). The incidence of coughing, restlessness and awareness of the intubation were significantly lower in group ? than in group ? (P< 0.05). The incidence of nausea coughing, restlessness and awareness of the intubation were significantly lower in group ? than in group ? (P< 0.01). The incidence of nausea, coughing, restlessness and awareness of the intubation were significantly lower in group ? than in group ? (P< 0.05). Conclusion Dexmedetomidine 1.0 礸/kg given via Ⅳ slowly on top of surface anesthesia with 1% tetracaine can provide a good intubation condition with less intubation response for conscious blind nasotracheal intubation. It抯 safe and effective. Key words: Dexmedetomidine; Conscious blind nasotracheal intubation; Conscious sedation