Objective:To observe the effect of Supplemented Siwu Decoction（SSWD） on blood pressure and left ventricular hypertrophy of spontaneous hypertension rats（SHR）.Method:Sixty SHR were randomly divided into six groups（n = 10

each）:SSWD high dose group（31.52 g.kg-1.d-1）

SSWD middle dose group（15.74 g.kg-1.d-1）

SSWD low dose group（7.81 g.kg-1.d-1）

model group（with normal saline）

Niuhuang Jiangya Wan group（0.17 g.kg-1.d-1） and Captopril group（7.88 g.kg-1.d-1）.SBP and left ventricular mass index（LVMI）

the content of left ventricular myocardical interstitial collagen and the collagen ratio of typeⅠto type Ⅲ at each groups were measured.Result:SSWD of high dose reduced SBP significantly compared with the model group（P < 0.01）

the antihypertensive effect was remaining and lasting during whole investigation.LVMI of high dose group reduced remarkly compared to that in the model group（P < 0.05）

the content of left ventricular myocardical collagen was lower than that in the model group

the deposition of left ventricular myocardical interstitial collagen of high dose group decreased pronouncedly compared to the model group.The outcomes from the microscope and elec-tronic microscope indicated that the damages in SSWD group were much slighter than those of the model group.Conclusion:SSWD could effectively lower blood pressure and led to regression of left ventricular hypertrophy in SHR.