Systemic chemotherapy is an integral component of the adjuvant treatment strategy for women who have early-stage breast cancer and accounts for significant improvements in breast cancer-specific mortality. Decisions regarding adjuvant therapy are increasingly complex with the advent of new therapeutic strategies, a growing body of literature on the molecular biology and natural history of breast cancer, and advances in therapeutic techniques and early detection. Ultimately, the risk-benefit calculus will continue to evolve in response to these advances and one hopes that clinicians will soon be able to tailor treatment recommendations to the biology of an individual cancer and the needs of the affected individual.