Paget's disease is a localised monostotic or polyostotic bone disease of unknown origin. It may be caused by a slow viral infection and/or genetic factors. It is characterised by increased bone remodelling and an initially excessive osteoclastic bone resorption, followed by a secondary increase in osteoblastic activity, leading to replacement of the normal bone by a disorganized, enlarged, and weakened osseous structure prone to deformities and fractures. The disease may be diagnosed by radiography, scintigraphy and biochemical tests. The primary aim of treatment is to reduce pain and risk of developing long-term complications. Potent antiresorptive drugs are now available, which control the increased bone remodelling and have led to a dramatic improvement in treatment. Zoledronic acid, a new generation of bisphosphonates, has the advantage of great potency and long duration of remission and a short infusion time.