During the past 15 years, medicine has witnessed several important advances in coronary artery reperfusion therapy for acute myocardial infarction (AMI). Both percutaneous transluminal coronary angioplasty (PTCA) and thrombolytic therapy have made significant advances in the early treatment of the AMI patient. Given both the shown benefit of these treatment modalities and the cardiac injury that they can prevent, it behooves the emergency physician (EP) to make a timely diagnosis of AMI to restore adequate perfusion and to salvage the maximum amount of myocardium. A correct diagnosis is dependent on EP expertise in the evaluation of the chest pain patient--in large part, the electrocardiogram.