LMWH (enoxaparin) should be used in combination with aspirin in the early phase of non-Q wave MI and in patients with unstable angina. The benefit of LMWH in acute coronary syndromes has been validated in several clinical trials. In addition, the use of LMWH is cost-effective when compared with use of UFH. The incidence of minor bleeding may be greater with LMWH than with UFH, most frequently due to ecchymosis at the injection site. However, the frequency of major bleeding did not differ between the two heparins. LMWH has been used successfully for the past 4 years by orthopedic surgeons in the prevention of pulmonary emboli. LMWH should replace UFH in the management of acute coronary syndromes.