Objective To observe and study the efficacy and mechanism of Yifei Xuanfei Jiangzhuo Capsule（ capsule to supplement the lung

diffuse the lung and downbear the turbid） for vascular dementia（ VaD）. Methods Totally 209 cases of VaD were randomized into the treatment group with 107 cases and control group with 102 cases. The treatment group was given 1. 75 g（ 5 caps） Yifei Xuanfei Jiangzhuo Capsule three times daily. The control group was given 0. 8 g（ 5 caps） repackaging capsules contained with Piracetam Tablets three times daily. Both groups were treated for 2 months. The scores of Hasegawa’s Dementia Scale（ HDS） and activities of daily living（ ADL） and the serum levels of superoxide dismutase（ SOD）

malondialdehyde（ MDA）

endothelin（ ET） and nitric oxide（ NO） were observed before and after treatment in both groups. The clinical efficacy was evaluated after treatment. Results The total effective rate of the treatment group and control group was 51. 40% and 48. 04% respectively

with no significant difference between groups（ P > 0. 05）. The scores of HDS and ADL were significantly improved after treatment in both groups（ P < 0. 05 or P < 0. 01）

especially ADL score in the treatment group（ P < 0. 05）. There was no significant difference between groups in the HDS score（ P > 0. 05）. The serum level of SOD was significantly increased but the serum levels of MDA

ET and NO were significantly decreased in both groups after treatment（ P < 0. 05 or P < 0. 01）

especially SOD and MDA in the treatment group（ P < 0. 05）. Conclusion Yifei Xuanfei Jiangzhuo Capsule is effective for VaD with an equivalent efficacy of Piracetam Tablets

which may be relevant to decreasing the serum levels of ET and NO and regulating the serum levels of SOD and MDA.