The fat embolism syndrome following trauma is associated with fat droplets in the pulmonary microvasculature. This is the first case report of a large adipose tissue embolus obstructing a pulmonary artery after blunt injury. This embolism occurred during the resuscitation of a patient with a laceration of an iliac vein and disruption of the adjacent fatty tissue secondary to a severe pelvic fracture. Theories of the pathogenesis of the fat embolism syndrome and implications for early therapeutic modalities are discussed.