Breast cancer represents a major health problem, with more than a million new cases and 370,000 deaths worldwide yearly. Options and understanding of how to use cytotoxic chemotherapy in both advanced and early stage breast cancer have made substantial progress in the past 10 years, with numerous landmark studies identifying clear survival benefits for newer approaches. Despite this research, the optimal approach for any individual patient cannot be determined from a literature review or decision-making algorithm alone. Treatment choices are still predominantly based on practice determined by individual or collective experience and the historic development of treatment within a locality. In many situations treatment decisions cannot be divorced from economic considerations. Blanket application of international, national or local guidelines is usually impractical or inappropriate and careful consideration of the detailed circumstances of each patient is required to make optimal use of available options. Recent research has allowed us to refine breast cancers further into prognostic groups based on a gene expression profile. Clinical trials to prove the value of this approach are currently being designed. This review discusses the evidence for various chemotherapy regimens in the adjuvant and metastatic settings, and examines the current evidence for the timing of radiotherapy in the adjuvant setting.