Despite an increasing incidence, the outlook for women with early breast cancer has improved considerably over recent years with a steady fall in the death rate in most western countries. This is due, at least in part, to the widespread use of adjuvant systemic therapy. However, some of these treatments have adverse effects on bone metabolism with increased bone loss which may result in osteoporosis and associated fractures. Most of the effects on bone are mediated by endocrine changes, either induction of an early menopause by chemotherapy and ovarian ablation, or further suppression of postmenopausal circulating oestrogens by aromatase inhibitors. There may also be direct effects of chemotherapy on bone cell function. The pathophysiology of osteoporosis in breast cancer patients, the methods of assessment and treatment options are reviewed. Bone health is a highly topical issue in breast cancer with the emergence of data supporting the use of several years of treatment with aromatase inhibitors. Guidelines on who and how to screen for bone loss, and simple, safe strategies for treatment to prevent osteoporosis are presented.