Embolism of fatty globules within the pulmonary circulation probably always occurs after trauma to bones, and within minutes of injury. The syndrome of fat embolism does not necessarily follow bone trauma. It occurs hours to days later, and the onset of symptoms and signs coincides with the peak serum non-cholesterol fat level. It is proposed that the syndrome of fat embolism is related to a chemical reaction caused by a raised neutral fat level in the pulmonary and systemic circulation. An attempt is made to formulate a logical treatment on the basis of the probable pathogenesis of the syndrome.