High dose bolus interleukin 2 (IL-2) used in the treatment of metastatic melanoma and renal cell carcinoma is known to have the potential for serious cardiac toxicity. At our institution 2 of 57 (3.5%) patients developed IL-2 induced myocarditis. The constellation of electrocardiographic changes and elevated troponin I is the hallmark of myocarditis. In this setting of high dose IL-2 therapy it is important to keep myocarditis in the differential in addition to the more frequently sought diagnosis of acute myocardial infarction. Although the gold standard for diagnosis is endomyocardial biopsy, there is considerable false negative rate. It may be reasonable to make the diagnosis on clinical grounds, while providing supportive care. Future investigation is required to better understand the pathophysiology and what factors may influence expression of this toxicity.