This chapter is a review of the current evidence for managing metastatic breast cancer. The treatment of metastatic disease is a complex one when compared to the early setting for which there is clear and high level of evidence. There has been a constant effort to improve survival in metastatic patients, but the incurable nature of the disease, its heterogeneity in terms of presentation and biology, the lack of well-designed clinical trials and the lack of acceptable endpoints have render it difficult. The fast introduction of new drugs makes the comparative standard arms used in most trials outdated, being difficult to generalise their results. A better understanding of the biology of disease is driving the development of new targeted agents as well as new methodologies for diagnosis and assessment of metastatic disease. This is shaping the design of new clinical trials in the metastatic setting with the aim of increasing the efficacy and tolerability of treatments. It is also an important goal in research how to best assess the psychosocial impact of this disease in patients and relatives life as well as the development of specific tools to measure quality of life in advance cancer.