Bone metastases are present in 65% of patients with advanced neoplastic disease and most of these present a rather slow clinical course characterized by pain, poor mobility and skeletal complications such as fractures and spinal cord compression. The literature shows that, in patients with breast cancer, myeloma and prostatic cancer, the administration of bisphosphonates are able to reduce the onset of skeletal complications, the need for RT and surgery. The aim of this prospective study is to evaluate the analgesic efficacy and tolerability of zoledronate, a new potent bisphosphonate. Sixty patients with painful bone metastases due to multiple myeloma or breast cancer or prostatic cancer will be treated with intravenous zoledronate (4 mg in 250 mL saline over 30 minutes) every 28 days for 6 months. Before the beginning of the study and respectively 3 days, 15 and 28 days after each infusion of zoledronate, the patients will be assessed regarding: pain intensity at rest and on moving, an eventual increase of pain due to the infusion (by means of a 6-level verbal scale: none, very mild, mild, moderate, severe, very severe), analgesic consumption, performance status, the need for RT and the onset of skeletal complications. The last assessment will be performed 2 weeks after the 6th infusion. Moreover, 3 and 15 days after each zoledronate infusion, the following adverse effects will also be assessed: fever, nausea, dyspnea, confusion, insomnia, vomiting, diarrhea, asthenia, abdominal pain (by means of a 6-level verbal scale: none, very mild, mild, moderate, severe, very severe) and hypocalcemia. Thirty-three patients have been enrolled: 14 of them concluded the 6-month treatment period, 11 patients withdrew due to disease progression and one was lost to the follow-up. The enrollment of the patients is still ongoing. The final results will be presented at the Congress.