Objective:To investigate effect of Shuangdan drop pills（SDP） on blood pressure and plasma angiotensin Ⅱ（AngⅡ） expression in patients with essential hypertension（EH） and to evaluate its safety.Method: Retrospective analysis from February 2009 to December 2011 for EH patients admitted with blood stasis syndrome were carried out in a sample of 200 cases.Methods of randomized

double-blind

double simulation

positive drug parallel control method were employed to divide the sample into treatment group and control group（1∶1

100 cases each）.The treatment group was given SDP 20 pills

tid

po;the control group was taken 10 mg enalaprilat

5 weeks for one course of treatment.Before and after treatment

dynamic blood pressure（ABPM） check and safety indexes（three conventional and liver

kidney） detection were carried out 24 h respectively.Radioimmunoassay was employed to measure plasma AngⅡ level in two groups before and after treatment.Result: In two groups

mean blood pressure during 24 h

daytime blood pressure mean

night blood pressure mean showed significant difference before and after treatment（P<0.05）;no significant difference was found between the two groups.The pressure fluctuation in two groups before and after treatment was significantly decreased（P<0.05）;and the treatment group was better than the controls（P<0.05）.In the two groups

plasma AngⅡ was significantly lowered after treatment（P<0.05）

and the effect in treatment group was better than the controls（P<0.05）.Conclusion: SDP has a good stable decompression effect

which is comparable to enalaprilat.SDP can effectively reduce the serum AngⅡ level in EH patients

with effect better than enalaprilat.