Objective To observe the effect and possible mechanism of Danhong Injection（ 丹 红注射液） on plaque stability and platelet activation of acute cornary syndrome（ ACS） patients after percutaneous coronary intervention（ PCI）. Methods Totally 320 ACS patients scheduled for PCI were randomly divided into routine group of 158 cases and Danhong group of 162 cases. Routine group were given oral aspirin 100 mg

once every day

clopidogrel 75 mg

once every day and atorvastatin calcium 20 mg

once every night. β-blocker

angiotensin converting enzyme inhibitor（ ACEI） and nitrate ester were added if necessary. Danhong group were additionally given Danhong Injection40 ml / d intravenous drip. Both groups began treatment at the day of PCI for 7 days. Detect the changes of soluble leukocyte differentiation antigen 40 ligand（ s CD40L）

platelet membrane glycoprotein CD62 p and GPⅡ b /Ⅲa receptor complex on the day of PCI and the 7th day after PCI. Results Plasma s CD40 L

platelet membrane glycoprotein CD63 and CD62 p of patients in both groups decreased significantly after treatment（ P < 0. 01）. Plasma s CD40 L

CD62p and GPⅡ b / Ⅲa receptor complex in Danhong group decreased more than those in routine group（ P < 0. 05 or P < 0. 01）. Conclusion Danhong Injection may stabilize intravascular plaque of ACS patients and inhibit platelet activation. The mechanism may relate to decreasing plasma s CD40 L

platelet membrane glycoprotein CD62 p and GPⅡ b /Ⅲa receptor complex.