The method of preventing reperfusion injury in reperfusion therapy is a medical technique for prevention of reperfusion injury in a patient where reperfusion therapy is necessary, such as following myocardial infarction (MI) or heat transplant in the patient. The patient is treated with intravenous immunoglobulin (IVIG) prior to an ischemic event or, alternatively, following the ischemic event, with the intravenous immunoglobulin providing cardio-protective effects to the patient for preventing reperfusion injury. The treatment with the IVIG may be used with any suitable type of reperfusion therapy, such as thrombolytic therapy, coronary angioplasty or coronary artery bypass surgery.