The pathological changes of pulmonary fat emdoiksm were studied in ratsby means of an intravenous injection with autosnbcutaneous fat.The resultsshowed that most fat ernboli appeared in pulmonary arterioles and capillariesafter 24 hours.By 4 days,large number of sudan Ⅲ-positive emboli were seenthroughout the lungs.The inflammatory cellular infiltration including the histoc-ytes,macrophages,polymorphonuclear leucocytes and occasional eosinophils,pulmonary edema and focal hemorrhage were observed.After 7 days,most fatemboli disappeared.No fat embolism in other organs was found.