Background Enoxaparin was shown to be superior to unfractionated heparin in the patients with non-ST-segment elevation acute coronary syndromes (ACS) in the Efficacy and Safety of Subcutaneous Enoxaparin in Non-Q-wave Coronary Events study and the Thrombolysis In Myocardial Infarction (TIMI) 11B trial. However, enoxaparin has had limited acceptance in clinical practice, in part because of the contemporary management of these patients, which includes glycoprotein IIb/IIIa inhibition and the use of early invasive management strategies. Study Design The Superior Yield of the New strategy of Enoxaparin, Revascularization and GlYcoprotein IIb/IIIa inhibitors (SYNERGY) trial is an 8000-patient, prospective, randomized, open-label, multicenter investigation of enoxaparin compared with unfractionated heparin in patients at high risk with non-ST-segment elevation ACS treated with an early invasive strategy. The primary efficacy end point is death or nonfatal myocardial infarction 30 days after enrollment. Implications The SYNERGY trial is the largest study currently planned for the acute therapy of patients with non-ST-segment elevation ACS and the first large trial since the publication of the revised American College of Cardiology/American Heart Association guidelines for the management of these patients. In addition to evaluating the potential superiority of enoxaparin over unfractionated heparin, this investigation will provide important observations of current treatment strategies in patients with ACS. (Am Heart J 2002;143:952-60.)