The results of available clinical studies suggest that breast cancer treatment significantly affect bone turnover, BMD and fracture risk. This is for instance the case for all third-generation aromatase inhibitors. For these reasons it is recommended that breast cancer patients exercise regularly and take daily calcium (1500 mg) and vitamin D (800UI) supplements. Most experts recommend that all women starting medical castration or aromatase inhibitor therapy should be assessed for their risk of osteoporosis and undergo bone mineral density (BMD) measurement by dual-energy X-ray absorptiometry (DEXA). Patients with pre-existing osteopenia and osteoporosis should be evaluated for conditions which worsen skeletal health, such as vitamin D deficiency, hyperparathyroidism, hyperthyroidism and hyper-calcuria. If these patients have a BMD score of -2.5 or lower, a low BMD (T-score between -1 and -2.5) and additional risk factors for osteoporosis or fragility fractures, bisphosphonate therapy should be considered. The optimal duration of bisphosphonate therapy is unknown. It should probably be given for as long as aromatase inhibitor therapy is continued. In addition, bisphosphonate therapy may also reduce the risk of bone metastases. This approach seems to be cost effective based on an economic evaluation model.