Objective: To observe the hypotensive effects of Qindan Capsule (芩丹胶囊, QC) on spontaneous hypertensive rats (SHR) and its effect on the contents of endothelin (ET), calcitonin gene-related peptide (CGRP) and angiotensin-Ⅱ(Ang-Ⅱ) in plasma and vascular tissues, and to investigate the possible mechanism of QC in lowering blood pressure.Methods: Forty SHRs were divided into 5 groups: the high dosage QC group [QCHD, 750 mg/(kg·d)], the low dosage QC group [QCLD, 150 mg/(kg·d)], the Niuhuang Jiangya Pill group [牛黄降压丸, NJP, 200 mg/(kg·d)], the Captopril group [15 mg/(kg·d)]and the model group, 8 in each group. Meanwhile, a normal control group consisting of 8 Wistar-Kyoto (WKY) rats was set up also. All the rats were administered with medicine through gastrogavage. Systolic blood pressure (SBP), level of ET, CGRP and Ang-Ⅱ in plasma and Ang-Ⅱ in tissues of mesenteric artery were detected in all the rats after 12 weeks of treatment. Results: The level of SBP after treatment in the QCHD group was lower than that in the model group (P<0.01), but with no significant difference as compared with that in the Captopril group and the NJP group (P>0.05). After treatment, the plasma level of ET was lower and CGRP higher than those in the model group (both P<0.05), and also higher than those in the NJP and Captopril group (both P<0.05). As for the content of Ang-Ⅱ, in mesenteric arterial tissues, it was lower in the QCHD group than that in the model group (P<0.05), but in plasma, it showed no significant difference between the two groups (P>0.05). Conclusion: QC has a satisfactory hypotensive action on SHR rats, and its mechanism may be associated with the regulation on plasma vasoactive peptide and regional renin-angiotensin system. Objective: To observe the hypotensive effects of Qindan Capsule (QC) on spontaneous hypertensive rats (SHR) and its effect on the contents of endothelin (ET), calcitonin gene-related peptide (CGRP) and angiotensin-II (Ang -II) in plasma and vascular tissues, and to investigate the possible mechanism of QC in lowering blood pressure.Methods: Forty SHRs were divided into 5 groups: the high dosage QC group [QCHD, 750 mg/(kg·d)], The low dosage QC group [QCLD, 150 mg/(kg·d)], the Niuhuang Jiangya Pill group [Niuhuang Jiangya Pill, NJP, 200 mg/(kg·d)], the Captopril group [15 mg/(kg ·d)] and the model group, 8 in each group. simultaneous, a normal control group consisting of 8 Wistar-Kyoto (WKY) rats was set up also. All the rats were administered with medicine through gastrogavage. Systolic blood pressure (SBP ), level of ET, CGRP and Ang-II in plasma and Ang-II in tissues of mesenteric artery were detected in all the rats after 12 weeks of treatment. Results: The level of SBP afte r treatment in the QCHD group was lower than that in the model group (P<0.01), but with no significant difference as compared with that in the Captopril group and the NJP group (P>0.05). After treatment, the plasma level of ET was lower and CGRP higher than those in the model group (both P<0.05), and also higher than those those in NJP and Captopril group (both P<0.05). As for the content of Ang-II, in mesenteric arterial tissues , it was lower in the QCHD group than that in the model group (P<0.05), but in plasma, it showed no significant difference between the two groups (P>0.05). Conclusion: QC has a satisfactory hypotensive action on SHR rats , and its mechanism may be associated with the regulation on plasma vasoactive peptide and regional renin-angiotensin system.