IN THE past few years the problem of thromboembolic disease as an important complication of surgical treatment has been repeatedly emphasized. In contrast fat embolism, though equally common, is seldom mentioned and is less often recognized clinically or pathologically, primarily because of failure to regard it as a possibility. Reports vary as to the incidence of fat embolism. Whereas clinicians feel that it is rare, positive evidence has been reported at autopsy in slightly less than one half of the bodies examined.1 In a recent series of 1,000 battle casualties, Wilson and Salisbury2 reported 8 cases with 6 deaths. Darrach3 reported 2 cases in a series of 12,000 cases of fracture and Groendahl4 stated that fat embolism is the cause of death in only 1 per cent of the deaths following fractures. On the other hand, Vance1b in a series of 246 routine autopsies found