Despite important advances in the management of non-ST segment elevation acute coronary syndromes, adverse outcomes remain common. The recent introduction of low molecular weight heparins and platelet glycoprotein IIb/IIIa receptor inhibitors is an opportunity to make a further impact on the mortality and morbidity of this common condition. Optimal use of these agents will likely result from the recognition of patients at a higher risk of an adverse outcome who are most likely to benefit. At the same time, identification of lower risk patients will avoid the use of unnecessary and potentially harmful medications. Guidelines for the application of these new agents were developed at three meetings of a multidisciplinary group of health professionals. Evidence for risk stratification of patients with non-ST segment acute coronary syndromes and the results of clinical trials for the individual antithrombotic and antiplatelet agents were reviewed. A practical algorithm for patient management is presented, which uses observations available to the physician in the first few hours after the onset of chest pain.