Fat embolism syndrome is a potentially serious and life threatening complication of long bone trauma, blunt trauma, and intramedullary manipulation. In long bone fractures, fat embolism is encountered in 0.9% to 2.2% of cases. During intramedullary manipulations, such as prosthetic stem insertion or reaming, the incidence is typically lower (range, 0.5% to 0.8%). Diagnosis is dependent upon the clinical recognition of dyspnea, petechiae, and cognitive dysfunction in the first several days following fracture, trauma, or intramedullary surgery. Treatment consists of pulmonary support and aggressive resuscitation. Studies support early fracture fixation, but the role of systemic steroids, heparin, and other modalities remains speculative.