Abstract: WT5”BZ]To explore the relationship between the expression of hepatitis D virus antigen (HDAg) and that of HBsAg/HBcAg in liver tissues of the patients with hepatitis D (HD) HDAg, HBsAg, and HBcAg in Paraffin-embedded liver tissue from 79 liver biopsy or autopsy samples from the patients with HD were studied with immunihistochemical double labelling techniques;meanwhile, compared with the expression of HBsAg/HBcAg in liver tissues of the patients with hepatitis B (HB) The detection rates for HBsAg and HBcAg in liver specimens of HD were 81% and 71%, and were lower than that of hepatitis B (94%, 92%) (P<0 05 or 0 01) HDAg was mainly expressed in nuclei of hepatocytes, much of positive cells were obviously aggregated in periportal region especially at the advanceing edges of areas of peicemeal necrosis, moreover, strong expression of HDAg was shown in the bolloming degeneration hepatocytes and hepatocytes near piecemeal necrosis region HBsAg was mainly expressed in cytoplasm of hepatocytes, and positive cells distribution were similar to HDAg positive cells HBcAg was mainly expressed in nuclei of hepatocytes, positive cells distribution were alone or focal type (3-5 cells) Double labelling studies showed those both HDAg and HBsAg might be mostly expressed in the same hepatocytes, and positive cells of HDAg and HBsAg were mostly found to locate in the same area of liver tissus, but HDAg coexisted seldomly with HBcAg, respectively the expression degrees and the positive cells disribution of HDAg and HBsAg were all obviously associated with the grades of pathological damage of liver tissus and necroinflammatory activity (p<0 01) [WT5”BZ]Conclution:[WT5”BZ]HDV infection can inhibit replication of HBV genome or expression of HBV antigen Becides of interactions between HBV and HDV, it is possible that direct cytotoxicity of HDV may play an impotant pathogenetic role in pathogenetic mechanisms of HDV [WT5”HZ]