Nonunion of a sacral fracture is a serious clinical condition: chronic pain, sitting discomfort, limp, neurological implications, and inability to work are frequent findings. Surgical treatment of these injuries often turns out to be technically difficult also for the expert pelvic surgeon and not infrequently provides poor radiographic and clinical results. The gold standard treatment at present is open excision, reaming of the nonunion site and internal fixation, performed by a multi-stage approach; as an adjunct, autologous cancellous bone grafting is usually performed in most severe cases. We report a case of a sacral nonunion in which traditional techniques failed, successfully treated by osteogenic protein-1 (BMP-7) application. The employment of BMPs demonstrated successful results in various types of fracture, but there is limited experience about their use in pelvic ring injuries: Further studies are necessary to better know the possible complications and to define their actual potential.