Prostate cancer is the most common cancer in men in many western countries. It is characterized by its propensity for bone metastases which occur in more than 80% of patients with advanced disease. Patients are at risk of complications including pain, hypercalcaemia, bone fracture and spinal cord compression. Hormonal treatment is the mainstay of treatment for these patients but most of them will then become hormone refractory. Bisphosphonates act by inhibiting osteoclast activities and are a potential therapeutic option for metastatic prostate cancer. In addition, they have been shown to reduce pain in patients with bone metastases as a consequence of multiple myeloma. Early uncontrolled studies of bisphosphonates in metastatic prostate cancer patients have shown encouraging results.