Abstract: Two-day-old SPF chickens were orally challenged with fowl adenovirus-VIII （FAV-VIII）.Then their livers were collected at different days post inoculation （dpi） and fixed in formalin.After paraffin embedding,paraffin section was stained by in situ hybridization.The results showed that staining mainly appeared in cytoplasm of sporadic or conglobate lymphocytes around necrotic foci or blood vessels.IFN-gamma mRNA became more at 5 dpi and was high at 20 dpi.It then decreased and disappeared at 30 dpi.This indicated that the mass ascent of IFN-gamma mRNA during the course of avian inclusion body hepatitis may be related to the increase of T lymphocytes.This also indicated that IFN-gamma,an immunopotentiator,was related to antivirus and recovery.