The clinical use of bone morphogenetic protein (BMP) in spinal fusion surgery has recently become controversial. After its approval by the US FDA in July 2002, BMP was adopted by many spine surgeons as a replacement for the more traditional iliac crest bone graft to avoid the complications associated with bone graft harvest. However, as broad clinical use escalated, reports increased of potentially serious complications associated with BMP. Controversy continues, particularly regarding the safety of BMP and whether it should routinely replace iliac crest bone graft for spinal fusion surgery.