Objective:To investigate the feasibility and security of midazolam for upper gastrointestinal endoscopy.Methods:487 patients requiring upper gastrointestinal endoscopy were allocated randomly to control group and drug group.The drug group was intravenously given midazolam 0.04～0.1mg/kg.The frequency of respiration

heart rate

blood pressure and oxygen saturation were measured in pre-examination

meta-examination and post-examination stage.The degree of amnesia

patient acceptance during the procedure were noted by a physician after the examination.Results:The incidence of total amnesia

meri-amnesia

unamnesia was 59.66%

26.10% and 11.25% respectively

and no complaints

complaints

unbearable complaints were 78.97%

19.31% and 1.71% in respectively drug group.The parameters of R

P

Bp and SPO

2

in pre-examination

meta-examination and post-examination stage were changed in the drug group.The changes were statistically significant （P

<

0.001）.The frequency of respiration accelerated during the procedure in the drug group

which was significantly different from that in the control group.（P

<

0.05）.There were no significant differences in heart rate and blood pressure between the drug and control group

P

>

0.05.The incidence rates of low SPO

2

in drug group and control group were 1.71% and 1.32% respectively during the examination

while 0.49% and 2.63% after the examination.The difference was not significant between the two groups（P

>

0.05）.There was no significant change in the parameters of each dosage groups（P

>

0.05）.Conclusion:The frequency of respiration is affected by midazolam

but heart rate

blood pressure and oxygen saturation are not.The dosage smaller than 0.1mg/kg of midazolam can produce safe and effective sedation for gastroscopy.