The anthracycline doxorubicin is a commonly used chemotherapeutic drug that induces cardiomyopathy in almost 10% of patients. The aim of this study was to examine the role of the leukocyte-derived enzyme Myeloperoxidase (MPO) in pathogenesis of anthracycline-induced Cardiomyopathy (AICM). We performed proteomics on whole heart tissue of MPO-deficient mice on C57BL/6J background and wildtype (WT) littermates seven days after intravenous injection of the anthracycline Doxorubicin (20 mg/kg bodyweight, dissolved in saline) or saline (NaCl).