A third of breast cancer diagnoses are made in women aged 70 years or over. Historically, older women have been regarded as presenting with tumors that are low grade and hormone sensitive and that are likely to have a good prognosis. However, in those older women whose tumors overexpress the HER2 oncogene, the prognosis is likely to be worse. Under these circumstances, due consideration should be given to adjuvant systemic therapy, including chemotherapy and targeted treatments, in order to minimize risks of disease recurrence. In this article we discuss the evidence base for the role of adjuvant systemic therapy in older women with HER2-positive early breast cancer.