About 50% of breast cancers occur in women aged 65 years and older, and both the incidence and prevalence of breast cancer among older women are expected to increase in the future. Aging implies a reduction in life expectancy and tolerance to treatments that should be considered in elderly patients with early breast cancer. In fact, treatment options often carry short-term risks and toxicities that might be tempered by long-term survival gains. The choice of adjuvant treatment for elderly patients should be based on the same criteria that are currently used for younger patients: endocrine responsiveness and assessment of risk of relapse. Adjuvant endocrine therapy should be considered for women with endocrine-responsive disease, regardless of age. The value of adjuvant chemotherapy is controversial. Older women are frequently undertreated with adjuvant chemotherapy and are underrepresented in clinical trials. In particular, no convincing data are available on the role of adjuvant chemotherapy in endocrine nonresponsive tumors, partly because most of the time these tumors represent a relatively small subset in adjuvant studies focusing on the elderly population. Several phase III trials are currently ongoing in elderly patients with early breast cancer to evaluate different options of adjuvant treatments. Only one trial, coordinated by the International Breast Cancer Study Group, is investigating the role of adjuvant chemotherapy for postmenopausal women of advanced age with endocrine nonresponsive early breast cancer. Disclosure of potential conflicts of interest is found at the end of this article.