Trastuzumab is a recombinant humanized monoclonal antibody with specificity for the extracellular domain of human epidermal growth factor receptor 2 (HER2). The use of trastuzumab administered sequentially or concurrently with adjuvant chemotherapy compared to chemotherapy in patients with HER2 positive was evaluated in several randomized trials. Many data concerning the incidence of adverse cardiovascular events acute, subacute and late are now available. The cardiac toxicity of anthracyclines may be acute, subacute and chronic. The acute toxicity occurs during or shortly after the infusion of the drug with arrhythmias, which in some cases leads to heart failure, pericarditis-myocarditis and electrocardiographic abnormalities. The acute toxicity is usually reversible in a dose-dependent manner. The acute and subacute toxicity are rare (1-4%). Data are available concerning clinically relevant cardiac toxicity with a chronic progressive deterioration of ventricular function up to heart failure.