Bisphosphonates (BPs) are approved as standard therapy in breast cancer for the treatment of bone metastases, since they were demonstrated to reduce the prevalence of skeletal-related events including fractures and hypercalcemia. In the adjuvant setting, BPs can be given to prevent and treat tumor therapy-induced bone loss in premenopausal and postmenopausal women and, owing to their beneficial effect on bone turnover, have also been evaluated for prevention of bone metastases occurrence. In this article we will review the mechanisms through which BPs have been demonstrated to prevent premetastatic niche formation and cell proliferation in bone lesions. Moreover, preclinical evidence of antitumoral effects of BPs will be presented and results from the most important clinical trials will be described critically. BPs may clearly play a clinically important role in early breast cancer in a postmenopausal adjuvant setting.