The purpose of this study is to investigate hypotensive effect of BDR-29, new herbal preparation of Cassiae Semen, Prunellae Spica, Uncariae Ramulus et Uncus, and Tribuli Semen, in stroke-prone spontaneously hypertensive rats (SHR-SP). SHR-SP were treated with BDR-29 at a dose of 100, 200 mg/kg/day orally for 13 weeks. In the BDR-29 treat group, mean blood pressure and systolic blood pressure were significantly reduced (p<0.05). In phenylephrine-precontracted arota and carotid artery, BDR-29 induced endothelium-dependent vascular relaxation. Hematological findings and biochemical examination revealed no evidence of specific toxicity related to BDR-29. In addition, BDR-29 was markedly attenuated intima-media thickness of thoracic aorta with progression of atherosclerosis. SHR-SP were treated with BDR-29 were significantly increased eNOS expression in arota. These results indicated that BDR-29 improves blood pressure as well as initial atherosclerotic lesion.