We observed two patients who developed moderate global myocardial dysfunction during therapy with high-dose interleukin-2 (IL-2). Although cardiac enzymes became markedly elevated at the completion of a full course of IL-2, patients exhibited no ischemic symptoms. Serial echocardiography documented global myocardial dysfunction, which resolved in 5 days in one patient but persisted beyond 4 weeks in another. Asymptomatic reversible myocardial injury can occur with high-dose IL-2 and can persist beyond 4 weeks after stopping therapy. Review of the literature suggests an IL-2-associated myocarditis as an etiology.