SEARCH FOR MORE EFFECTIVE ANTICOAGULATION: The limitations of conventional treatment with non-fractionated heparin (NFH) in patients with unstable angina and myocardial infarction without Q wave are demonstrated by the 7 to 9% rate of serious complications (infarction and/or death) at 30 days and has motivated search on the use of low-molecular-weight heparins (LMWH). PROVEN CLINICAL EFFICACY: As early as 1995, a pilot study reported the superiority of the aspirin-LMWH (nadroparin) combination compared with aspirin alone or the aspirin-NFH combination. In 1996, the FRIC study compared for the first time a LMWH with conventional NFH and reported rather disappointing results with LMWH (dalteparin). However, the ESSENCE study showed the success of LMWH (enoxaparin) versus NFH in unstable angina and infarction without Q wave. A MORE COMFORTABLE PRESCRIPTION: The subcutaneous administration, the lack of a need for laboratory tests, better predictability of the anticoagulant effect and better tolerance are powerful arguments favoring LMWH for use in unstable angina and infarction without Q wave. ROLE IN THE MANAGEMENT OF ACUTE CORONARY PATIENTS: LMWH have come to play an important role in the management of uncontrolled coronary artery disease where treatment protocols are evolving rapidly with the development of new antiplatelet compounds. The requirement for prolonged oral antiplatelet or LMWH treatment in ambulatory patients after an acute coronary event remains to be evaluated.