Bisphosphonates have a set place in the treatment of osteoporosis in adults. For the last 10 years they have also been used in pediatrics. Due to inhibition in differentiation and reduction in osteoclasts, both pamidronate and alendronate, the most commonly used preparations, cause an increase in bone density. Most experience comes from the i.v. treatment of forms with severe courses of osteogenesis imperfecta (OI). There is an increase in bone substance, a decrease in rate of fractures and a reduction in pain with higher mobility of those effected. In addition to the use of drugs, intramedullary nailing and physiotherapy are important therapeutic standards. Bisphosphonates are also used for other diseases involving bone remodeling, such as juvenile idiopathic osteoporosis or familial hyperphosphatemia. Acute side effects usually occur with the first infusion, involve "flu-like" symptoms and are self limiting. The question of long-term side effects cannot be answered with the currently available data.