ABSTRACT— Hepatocellular blood plasma inclusions were demonstrated in conventional formalin-fixed paraffin-embedded liver tissue by the immunoperoxidase technique in 114 out of 197 liver specimens. They were usually round or elliptical in shape, their size varying from a few μm to about 30 μm in diameter. Albumin, fibrinogen, α1-antitrypsin, IgG, IgM, IgA, ceruloplasmin and transferrin were demonstrated in the inclusions, in that order of frequency. A majority were negative with the periodic acid Schiff stain after amylase digestion, but a few were positive. Many of them seemed to correspond to vacuoles in the hepatocytes but some were not seen in HE-stained sections. The inclusions were frequently seen in autopsy liver specimens, but were rare in surgical ones. Most of the inclusions might develop at an agonal stage, probably as a result of hypoxia or circulatory disturbances in the livers.