The 1st autopsy case of a patient treated with perfluorochemicals (PFC) for hemolytic anemia, occurring after an operation for dissecting aneurysm, is reported. Preliminary histopathological experiments after administration of PFC in rabbit are also described. In this human case and experimental animals, the reticuloendothelial organs, blood monocytes and macrophages including histiocytes were markedly blocked in their phagocytic activities in every portion of the organs examined, and transformed themselves into ballooning foamy cells upon administration of PFC. Morphologically, the excretion of this chemical from either the lung or the urinary system was not established. PFC particles are still found in the cytoplasm of cells in various organs 4 mo. after PFC administration. Further studies are necessary regarding the use of PFC in human beings.