Ｏｂｊｅｃｔｉｖｅ　To investigate the effects of a loading dose of dexmedetomidine(Dex) on the hemodynamics of children with obstructive sleep apnea-hypopnea syndrome(OSAHS) during total intravenous anesthesia and total inhalation anesthesia.　Methods　A total of 50 patients scheduled for adenotonsillectomy were enrolled in the study, and randomly divided into a total intravenous anesthesia group (group A) and an inhaled anesthesia group (group B) (n=25). After anesthesia induction, both groups were given a loading dose of Dex (1 μg/kg over 10 min). The systolic blood pressure(SBP), diastolic blood pressure(DBP), mean arterial pressure(MAP) and heart rate were recorded before infusion(T0), 5 min(T5) and 10 min(T10) after administration of Dex.　Results　Compared with baseline values, group A presented remarkable increases in SBP, DBP and MAP at T5 and T10(P<0.05). Group B demonstrated decreased SBP, DBP and MAP 10 min after infusion(P<0.05). The heart rate in the both groups were significantly decreased after Dex infusion(P<0.05).　Conclusions　During anesthesia maintenance, a loading dose of Dex can significantly increase arterial blood pressure in OSAHS patients when combined with total intravenous anesthesia, and significantly decrease arterial blood pressure when combined with inhaled anesthesia.