Among 45 autopsy cases (including 13 cases as control), which have had in our laboratory from July 1956 on ward, the author picked out the lung and in some cases, heart, kidney, cerebrum, spleen, and liver, and examined microscopically the existance of fat embolus in the organs by means of Sudan Ⅲ Haematoxylin staining (Daddi method), after 10% formalin fixation. According to the degree of fat embolism, the author divided into six groups from zero to five and compared. He has arrived at the result as follows: 1) Among 45 autopsy cases 35 cases male, 10 cases female), there were no relations between gender and fat embolism. 2) Among 45 autopsy cases, there were no relations between age and fat embolism (9 cases under age 20, 24 cases age 21 to 40, and 12 cases over age 41). 3) Among 45 autopsy cases, there were confirmed the high degree of fat embolism in the lung in case the dead bodies have been left for about one or a few hours after wounded than those of sudden death. There were 30 cases with the sudden death or closely sudden death, 2 cases for about one hour after wounded, 9 cases for a few hours to fourteen or fifteen hours, and 4 cases from 4 to 10 days after injury. 4) Concerning with the time after death, there were 41 cases with from 6 to 24 hours, one case about 36 hours, 3 cases about 5 to 7 days and one case not cleary. 5) Among autopsy cases with hurt, there were 14 cases of injury on bones, one case of cut wound and subcutaneous bleeding, 15 cases of punctured wounds, and one case of incised wound, it is confirmed that, in all cases of injury on bones the fat embolism in the lung were from one to four. Among 15 cases with punctured wounds, there has been proved one degree in 8 cases, but zero in 7 cases, and in cut wound, subcutaneous bleeding and incised wound cases, there has been proved from one to three. As mentioned above, it could be supposed that there were high degrees of fat embolism in dull edged hurt rather than in sharp edged hurt. 6) As to 32 autopsy cases with hurt, there were divided according to the parts of hurt; 8 cases on head and face, 3 cases on cervical region, 11 cases on breast (back), 2 cases on abdomen, one case on hands and foots and 7 cases more than two parts of body. Among 9 autopsy cases found in the lung with over three degrees there were 6 cases with hurt on head or face, which showed strong fat embolism than the other parts of body. 7) As to 13 autopsy cases picked up for control (asphyxia, intoxication, drowning, disease and burns), there were nothing to be shown in any case but in case of burns, one degree in the lung. 8) There were proved fat embolism in the lung in case of vertebral fracture. 9) There were also proved fat embolism in the lung in all cases being run over and killed (4 cases); in both cases the train accident was remarkably showed three degree of embolus. 10) As to the fat embolism in the lung, it was remarkably shown in the left lung than the right, and stronger in lower lobe than in upper and middle lobe. 11) The degrees of the fat embolism on the organs were higher in the lung than in the other organs, and the existance of fat embolism in the other organs had no significance.