The widespread use of adjuvant systemic therapy, to some extent, contributes to the steady fall in the mortality of early breast cancer patients over recent years. However, some of the treatments have adverse effects on the bone metabolism with increased bone loss which may result in osteoporosis and associated fractures. Most of the effects on the bone are mediated by endocrine changes, either induction of an early menopause by chemotherapy and ovarian ablation, or further suppression of postmenopausal circulating estrogens by aromatase inhibitors. Chemotherapy may also have direct effects on bone cell function. Bone health of breast cancer patients is a highly topical issue with increasing data supporting the use of aromatase inhibitors in recent years.