Acute coronary syndrome (ACS) refers to the spectrum of cardiac disease, from unstable angina to ST-segment-elevation myocardial infarction. In the emergency medical services (EMS) setting, ACS may be more broadly thought to include patients with chest pain or other symptoms believed to have a cardiac origin who have evidence of ischemia or acute myocardial infarction on a 12-lead electrocardiogram, or symptomatic patients with a previous cardiac event or known cardiac disease. Pharmacologic management of these patients is based on the use of three primary classes of drugs: those that affect clotting, those that establish and maintain hemodynamic control, and those that relieve pain. Many of these agents have been evaluated in large clinical trials for in-hospital use, and a number of ongoing studies are assessing their efficacy in the prehospital setting. The appropriateness of prehospital use of specific agents within each class depends on proper patient selection, the necessity of immediate intervention, ease of use in the field, expertise of EMS personnel, and cost-effectiveness of therapy. This consensus group reviewed agents from all three classes (including aspirin, GPIIb/IIIa inhibitors, unfractionated and low-molecular-weight heparins, fibrinolytics, beta-adrenergic blockers, calcium antagonists, nitrates, and morphine) for their overall indication, applicability to the prehospital setting, and current prehospital use.