Chemotherapy plays a central role in the treatment of breast cancer for the majority of patients at all resource levels. Chemotherapy improves survival, reduces recurrence and has the capacity to improve candidacy for definitive surgery or for breast conservation when used before surgery. It can also be used to palliate painful symptoms of advanced disease. Over the past 35 years, the effectiveness of systemic therapy (including chemotherapy) has improved and together with increased efforts in early detection, systemic therapy has contributed to major improvements in breast cancer survival. Studies suggest that tumor biology (which may differ among patients) affects response to chemotherapy, thus requiring tumor pathology studies prior to initiation of treatment regimens. The toxic side-effects of chemotherapy and the resources to monitor for and manage toxicity must be considered in chemotherapy treatment planning.