Aim To investigate whether serum levels of matrix metalloproteinase(MMP) are associated with the degree of risk in patients with acute coronary syndromes(ACS). Methods Using SDS-PAGE Zymography and Western-Blotting,Serum Pro-MMP-2,MMP-2 were measured in 78 patients ACS,28 with unstable angina(UA) and 50 with acute myocardial infarction(AMI).Control group includes 50 healthy volunteers.51 cases were in stable angina group. Results Serum MMP-2 was significantly increased in both UA(455±51 INT·mm~2)and AMI group(503±45 INT·mm~2)compared with those in control group(236±33 INT·mm~2) and stable angina(224±23 INT·mm~2)(p<0.05,respectively)by Zymography.But there was no difference between UA and AMI group(p<0.05),and there were no difference between each two subgroups of UA(which are defined low-risk,mid-risk and high-risk group) in duration time of ischemia,ECG and CK-MB/cTnI. Conclusions Increased serum level of activity MMP-2 was detected in patients with ACS.Their findings provide an insight into the unstable plaque association with MMP-2.Serum MMP-2 level appears to be a marker of plaque unstable in patient with acute coronary syndrome.