Objective:To evaluate the efficiency and safety of fraxiparin in the treatment of patients with ACS. Method:137 patients with acute coronary syndrome(ACS)were randomly assigned to fraxiparin treatment and enoxaparin treatment for 7 days.Result:129 cases completed the whole trial and the results were obtained from ITT.The heart death rate was not statistically different between the two groups during the treatment.No Q segment acute myocardial infarction occurred.Both drugs statistically decreased CK CKMB and TnT.There was no significant difference between the two groups regarding these changes.Only two minor adverse reactions occurred and became normal soon after nadroparin withdrew. Conclusion:Fraxiparin and enoxaparin had similar efficiency and safety in the treatment of patients with ACS.