Purpose To update the formal expert consensus-based guideline recommendations for practicing oncologists and others on the management of brain metastases for patients with human epidermal growth factor receptor 2-positive advanced breast cancer to 2018. Methods An Expert Panel conducted a targeted systematic literature review (for both systemic treatment and CNS metastases) and identified 622 articles. Outcomes of interest included overall survival, progression-free survival, and adverse events. In 2014, the American Society of Clinical Oncology (ASCO) convened a panel of medical oncology, radiation oncology, guideline implementation, and advocacy experts, and conducted a systematic review of the literature. When that failed to yield sufficiently strong quality evidence, the Expert Panel undertook a formal expert consensus-based process to produce these recommendations. ASCO used a modified Delphi process. The panel members drafted recommendations, and a group of other experts joined them for two rounds of formal ratings of the recommendations. Results Of the 622 publications identified and reviewed, no additional evidence was identified that would warrant a change to the 2014 recommendations. Recommendations Patients with brain metastases should receive appropriate local therapy and systemic therapy, if indicated. Local therapies include surgery, whole-brain radiotherapy, and stereotactic radiosurgery. Treatments depend on factors such as patient prognosis, presence of symptoms, resectability, number and size of metastases, prior therapy, and whether metastases are diffuse. Other options include systemic therapy, best supportive care, enrollment in a clinical trial, and/or palliative care. Clinicians should not perform routine magnetic resonance imaging to screen for brain metastases, but rather should have a low threshold for magnetic resonance imaging of the brain because of the high incidence of brain metastases among patients with HER2-positive advanced breast cancer. Additional information is available at www.asco.org/breast-cancer-guidelines .