Treatment of breast cancer (BC) in the elderly is especially challenging as they show physiologic changes, functional deficits, comorbid medical conditions, and polypharmacy. Geriatric assessment can identify such deficits, predict treatment toxicity, and may lead to interventions that improve quality of life and preserve function. This chapter recommends mammography screenings in women above 65 annually or biennially provided they have at least a 10-year average life expectancy, and after discussion of the risks and benefits. Endocrine therapy is the mainstay adjuvant treatment for older women with early stage BC and HR positive tumors. Older patients with BC have similar benefits from chemotherapy as younger patients, but are at greater risk from toxicity. Adjuvant radiation therapy might be omitted in older patients with small, node negative, HR positive tumors. In metastatic breast cancer, endocrine therapy is the cornerstone of treatment for HR positive tumors and chemotherapy for triple negative tumors.