The inhibition of thrombin plays a key role as adjunct therapy in the management of patients with primary percutaneous coronary intervention for ST elevation myocardial infarction. Enoxaparin provides a more predictable and constant level of anticoagulation compared with the current standard unfractionated heparin. The available data from smaller studies and prospective registries suggest that enoxaparin is associated with a reduction in the rate of death and nonfatal reinfarction after primary percutaneous coronary intervention without an increase in bleeding complications. Thus, a large randomized trial is warranted to further evaluate the role of enoxaparin in these patients.