Abstract: Objective: To investigate the productions of MMP2 and MMP9 from circulating monocytes in patients with acute coronary syndrome,and alternations of them after myocardial ischemia or myocardial infarction,and to discuss the action of these two gelatinases on pathogenesis of acute coronary syndrome Methods: The contents of MMP2 and MMP9 in supermatart of cultural monocytes from 38 UA,16AMI,22 SApatients and 18 Control subjects were measured by ELISA kit Moreover,the alternations of two gelatinases after myocardiaol ischemia,in the time course of myocardial infarction,and the relationship between MMP2,MMP9 and serum Ck/Ck MB were analyzed respectively Results: The productions of MMP2 and MMP9 of circualting mnocytes from patients with UA,AMI group were greater than those from control subjects （MMP2: P＜ 0.0001;MMP9: P＜ 0.0001） and patients with SA（MMP2: P＜ 0.0001;MMP9: P＜ 0.0001） The contents of MMP2 and MMP9 were almost unchanged after onset of myocardiaol ischemia or in the first 72 hours after myocardial infarction,and they were not correlated with serum Ck/Ck MB Conclusion: The productions of MMP2 and MMP9 in circulating monocytes from patients with UA and AMI were increased,and were not affected by myocardiol ischemia or infarction As a result,they might participate in pathogenesis of acute coronary syndrome.