-Lipid embolism is a serious and life-threatening problem and usually arises as a complication of severe trauma associated with long bone or pelvic fractures. It is generally thought that fat droplets enter the circulation at the site of fracture. In the systemic circulation, they become emboli to brain, kidney and other areas. Lipids are absorbed from the intestinal tract and trans ported into pulmonary tis sue via thoracic duct and ex posed to first catabolic procedures in the lungs. We have predicted that systemic lipid embolism may not occur unless bone fractures lead to pulmonary in jury. This study was planned to investigate this hypothesis with respect to the role of pulmonary contusion and long bone fractures in the formation of cerebral fat embolism. Twenty male hybrid rabbits were included in this study. Pulmonary contusion was per formed on half of the rabbits (n = 10) and femur fracture was applied to the remaining ones (n = 10). Ten days after procedure, all rabbits were sacrificed. Brain specimens were taken by frozen-section method and stained with Sudan black. Intraarteriolar lipid particles in the brain were examined microscopically. Cerebral fat embolism was detected in seven animals exposed to pulmonary contusion and only in one animal exposed to femur fracture. The mean number of branches of middle cerebral artery at midparietal level occluded with fat particles were higher in the pulmonary contusion group than in the long bone fracture group. In conclusion, we found that pulmonary contusion had more deleterious effects than long bone fracture in the formation of cerebral fat embolism.