This therapy, with a total effective rate of 90%, was satisfactory for all syndromes and various kinds of UA. Those cases with plasmal NO and t -PA lower than normal recovered to certain extent after the treatment. But there was no effect on plasmal ET after treatment, indicating that the mechanism of Shen - yuan - dan may be partially due to the repair of vessel endothelium, lowering of vessel tension, decrease of unstable thrombus through the regulation of plasma NO, t -PA level, hence, the improvement of coronary blood supply.