Objective To investigate the effect of intramuscular dexmedetomidine before induction of general anesthesia on the incidence of fentanyl-induced cough. Methods A total of 200 ASA Ⅰ-Ⅱ patients were randomly allocated into four groups (C,D1,D2,and D3; n=50) and administered intramuscularly dexmedetomidine 0,1,1.5,2 µg/kg, respectively. 15 min later,all patients received intravenous fentanyl 3 µg/kg, and subsequently intravenous propofol 2 mg/kg and rocuronium 0.6 mg/kg for anesthetic induction. The incidence and severity of cough within 1 min after fentanyl administration,noninvasive blood pressure and heart rate were recorded. Results The incidences of cough in group D1,D2,and D3 were lower than that in group C(P ＜0.01), while there were no significant differences between D1,D2,and D3(P ＞0.05). There was no significant difference in noninvasive blood pressure and heart rate before fentanyl injection compared with baseline for all the four groups(P ＞0.05). The incidence of severe low blood pressure in group D3 was higher than that in group C (P ＜0.01), and the incidences of severe sinus bradycardia in D2,and D3 were higher than that in group C(P ＜0.01),while there was no significant difference in severe low blood pressure and sinus bradycardia between group C and group D1(P ＞0.05). Conclusions Pretreatment with low dose(1 µg/kg) of intramuscular dexmedetomidine significantly reduced the incidence of fentanyl-induced cough without significant hemodynamic changes during induction of general anesthesia.