The cytochemical characteristics of the hepatitis B virus (HBV) components, the nuclei and cytoplasm of the infected cells were studied in liver needle biopsy material obtained from patients suffering from serologically HBsAg positive chronic hepatitis. The HBV surface and core components were found to be more resistant to proteolytic enzymes and phospholipase than the other cellular components, and only combined digestion was effective. With preferential RNP and specific DNP staining the accumulation of granules 10-20 nm and 20-40 nm in diameter could be observed in the liver cell nuclei. The cytochemical-morphological polymorphism of the latter was well detectable. Part of the granules corresponded to accumulated perichromatin granules. It is assumed that the groups of granules 20-40 nm in diameter, showing a varying density on DNP staining, similar to the chromatin on RNP staining, and not surrounded by a peripheral area represents one of the forms of appearance of the HB virus core component.