The fat embolism syndrome is a complication which encounters rarely after fractures of pelvis and long bones of lower extremity of severe injury of soft tissue, and may results in microinfarctions in lungs, brain, heart, kidneys and other important organs when fat globules flow from bone marrow into small vessels. And that is the one of the main cause of death within 72 hours after major trauma of long bones. Diagnosis of fat embolism syndrome was made by clinical criteria by Gurd, but, majority of cases didn't show characteristic clinical symptoms or signs. Recently CT and MRI of the brain are adopted to the diagnosis of FFS as a new method. Authors experiences six cases of fat embolism syndrome from Mar. 1991 to Mar. 1994 and analyzed the brain MRI findings. We concluded that the brain MRI findings such as diffuse brain swelling, petechial hemorrhage and microinfarctions were helpful to diagnose clinically apparent or subclinical fat embolism syndrome.