Bisphosphonates are synthetic analogs of pyrophosphate which have an affinity for hydroxyapatite. These drugs act primarily on osteoclasts, impairing the development of immature osteoclasts and the function of mature osteoclasts, as well as depressing chemical signaling to adjacent cells, resulting in a shift in the balance of deposition and resorption in bone. Conditions for which bisphosphonates are being used in children include four broad categories, 1) a primary defect in bone mineralization 2) bone matrix abnormalities 3) bone abnormalities due to systemic disease or the effects of treatment of systemic disease or 4) significant soft tissue calcification with no bone abnormality.