Breast cancer is a devastating illness but cure rates are increasing and as they do the secondary effects of breast cancer treatment on bone are becoming more prominent. Of particular concern is the increased fracture rates and dramatic bone loss seen in studies of patients undergoing therapy with aromatase inhibitors. Recently a UK Expert Group has drawn up guidelines for the prevention of bone loss. The main recommendations can be summarised as follows: Bone loss in women who experience a premature menopause due to treatment before the age of 45 or who are receiving ovarian suppression therapy is accelerated by the concomitant use of aromatase inhibitors. As they are at high risk of significant bone loss they should have a baseline dual energy X-ray absorptiometry (DXA) assessment of BMD. As randomised clinical trials in postmenopausal women indicate that bisphosphonates prevent the bone loss and accelerated bone turnover associated with aromatase inhibitor therapy their use as the main preventative therapy is recommended, along with a healthy lifestyle and adequate intake of calcium and vitamin D. Decisions on the initiation of treatment initiation should be based on a combination of risk factors for osteoporotic fracture and BMD levels. Due to the rate of bone loss associated with breast cancer treatments, and uncertainties about the interaction between aromatase inhibitor use and BMD for fracture risk, the thresholds for intervention have been set at a higher levels than generally recommended for postmenopausal osteoporosis.