Zoledronic acid 4 mg administered as a 15-minute infusion every 3-4 weeks is effective and well tolerated in the treatment of patients with breast cancer metastatic to bone. It is effective in reducing complications arising from metastatic bone disease in this patient population, with a clinical profile that compares favourably with that of pamidronate. Zoledronic acid administered on a less frequent schedule (every 3-6 months) has also shown potential in preventing cancer treatment-induced bone loss in pre- and postmenopausal women with breast cancer receiving adjuvant hormonal therapy. Preliminary data suggest that zoledronic acid may have antitumour effects, which may reduce the risk of overall disease progression in patients with malignant disease. Thus, zoledronic acid has a well established role as first-line treatment in patients with bone metastases secondary to breast cancer, and may prove useful as a preventive treatment for cancer treatment-induced bone loss or an adjuvant therapy in women with breast cancer.