To describe new clinical findings, efficacy, and safety regarding the use of targeted agents in the treatment of HER2-positive metastatic breast cancer. Published research articles, abstracts, and clinical experience. HER2-positive cases of breast cancer tend to be more aggressive and more likely to become resistant to therapy than HER2-negative tumors. The current standard approach to patients with HER2-positive metastatic breast cancer includes the use of trastuzumab. Because cellular mechanisms can arise that can block the efficacy of this approach (and result in clinical resistance), recent research has led to the development of lapatinib, a targeted therapy that can act on HER2 inside the cell to disrupt the signaling pathways thought to be part of tumorigenic mechanisms. Oncology nurses should be aware of the treatment strategies for HER2-positive metastatic breast cancer and its limitations, which is essential for providing optimal nursing care.