A significant milestone in the treatment of breast cancer is the identification of the HER2 receptor as a drug target for cancer therapies. Trastuzumab (Herceptin), a monoclonal antibody that blocks the HER2 receptor, is among the first of such drugs approved by the US Food and Drug Administration for targeted cancer therapy. Clinical studies have shown that Trastuzumab significantly improves the overall survival of breast cancer patients. However, an unforeseen significant side-effect of cardiotoxicity manifested as left ventricular dysfunction and heart failure. Concurrent studies have demonstrated the essential role of the HER2 receptor in cardiac development and maintaining the physiological function of an adult heart. The HER2 receptor, therefore, has become a critical link between the oncology and cardiology fields. In addition to Trastuzumab, new drugs targeting the HER2 receptor, such as Lapatinib, Pertuzumab and Afatinib, are either approved or being evaluated in clinical trials for cancer therapy. With the concern of cardiotoxicity caused by HER2 inhibition, it becomes clear that new therapeutic strategies for preventing such cardiac side effects need to be developed. It is the intent of this paper to review the potential cardiac impact of anti-HER2 cancer therapy.