Objective：To evaluate the effect of dexmedetomidine（DEX） combined with propofol on the postoperative cardiovascular responseses，inhibition index of energy and recovery time in patients undergoing eleotroconvulsive therapy and to investigate the effi－cacy and the security of dexmedetomidine combined with propofol for ECT． Methods：Sixty MECT patients were randomized into two groups：DEX group（n=30），with DEX 1.0 μg/kg，administered 10 min preoperatively； and NS group（n=30），with normal saline of the same volume administered．Anesthesia was induced with propofol till appearance of slow wave sleep by dynamic electroencephalogra－phy（EEG） or disappearance of lash reflex． Then succinylcholine 1/（mg·kg） was administered． Mean arterial blood pressure（MAP） and Heart rate（HR） were recorded prior to anesthesia，10 min after DEX administration and at each time point after MECT were recorded as well as seizure duration，the inhibition index of energy and the time points of resuscitation． Results：Compared with NS group，HR and mean arterial pressure（MAP） in the DEX group declined 10 min after administration and 1 min and 3 min after seizure and the time points of resuscitation. While the differences at 1 min and 3 min had statistical significance（P<0.05），and the peaks HR and MAP were lower in the dexmedetomidine groups compared with the NS group（P<0．05）． However，the inhibition index of energy in the DEX groups were similar to those in the NS group（P>0．05）． But the resuscitation time was markedly retarded in DEX group in comparison with NS group（P>0．05）． Conclusion：DEX 1.0 μg/kg Ⅳ slowly administered over 10 min before the induction of anesthesia with propofol is safe and effective for MECT．