Effective treatment for breast cancer can produce a reasonably good ten-year survival rate in comparison to many other cancer sites. Nevertheless, the potential psychological, sexual and physical dysfunction caused by both the diagnosis and treatments can have a deleterious impact on the quality of a woman's life. The range of possible treatments may have similar outcomes in terms of response and survival, but can produce very different effects on emotional well-being. Therefore, monitoring quality of life in breast cancer should be a mandatory part of follow-up in clinical trials. Data derived from various studies of quality of life can also be used to assist the doctor and patient in decision-making about treatment options. Furthermore, assessment of quality of life can help identify those patients who might profit from psychosocial interventions. In this paper some of the instruments used to assess quality of life in breast cancer will be discussed.