The stress associated with cancer development leads to disturbances in the hypothalamic-pituitary-adrenal axis and suppresses important facets of the immune response. The use of complementary therapies in the treatment of women with breast cancer has demonstrated therapeutic benefits that entail improvements in the patients' quality of life. The objective of this article is to present evidence on the use of complementary therapies as a stress reduction strategy and on its stimulating effects on the immune system of women with breast cancer. This is a reflexive updating article that will support the health professionals' understanding on the use of complementary therapies in breast cancer care. The use of complementary therapies in the treatment of women with breast cancer has significantly improved these subjects' stress, depression, fatigue, anxiety, and consequently, their quality of life, as well as their immune response, which is mainly illustrated by the increased number and cytotoxic activity of natural killer cells. Clinicians, health professionals and patients need to be cautious about using complementary therapies and fully understand the real benefits and risks associated with each therapy. Little or no supporting evidence is available to clarify the effects on the immune system of women with breast cancer, and the consequent therapeutic benefits obtained through the use of these practices.