Intracellular structures of hepatocytes were studied in rats intoxicated with carbon tetrachloride (CCL4) by scanning electron microscopy (SEM). Liver tissues were treated successively by conductive staining, critical point drying and fracturing with a scalpel. Fractured hepatocytes were mainly observed in the specimens 12 hours after CCL4 administration, Hepatocytes near the portal tract showed a normal dense cytoplasm. Swollen foamy hepatocytes were remarkable in the intermediate zone. They had numerous vesicles, 0.6-2.5 micrometer in diameter, which correspond to dilated cisternae of rough endoplasmic reticula (RER) observed by transmission electron microscopy. The vesicles were separated by a thin rim of the cytoplasm and communicated with each other through a round window. Besides vesicles, the foamy hepatocytes had some vacuoles 3-10 micrometer in diameter, which were extremely dilated RER. The vacuoles had many windows and communicated with the vesicles. Hepatocytes with dense cytoplasm and many vacuoles were distributed widely in the lobule. They were intermingled with the vesiculated hepatocytes inthe intermediate zone. Their vacuoles were 1.5-3.0 micrometer in diameter and some vacuoles communicated with each other. The vacuole had a well-developed wall with 0.1 micrometer diamter pores. The pores were sometimes arranged in line. Hepatocytes near the central vein showed necrotic changes. Most membraneous structures were disrupted except for fat droplets and the nucleus. The nucleoplasm was looser and nuclear pores disappeared. In summary, SEM demonstrated three-dimensionally organelle changes of hepatocytes induced by CCL4 administration.