Recent advances have allowed elucidation of the factors which are important to the healing of bone fracture. The bone morphogenetic proteins (BMPs) of the transforming growth factor-beta (TGF-beta) family have emerged as an effective therapeutic target in the treatment of severe fractures and fracture non-unions which have been resistant to conventional treatment. Treatment with BMP has provided encouraging results, both in animals and humans. Such treatments have reduced the time required for a fracture to heal and have increased the strength of the healed bone. BMP antagonists have been shown to modulate BMP activities in diverse and critical ways in a myriad of tissues and systems during normal vertebrate development. Recent studies have begun investigating the role of BMP antagonists during bone development and in healing of fractures. Better understanding of the effects of such antagonists in the healing of fractures opens the possibility of enhancing those effects which are exerted solely by treatment with BMP.