On liver biopsies of 20 children with different forms of chronic HBsAg-positive hepatitis, submitted to immunodepressive treatment, the presence and the distribution of core and delta antigens and their correlation with the different clinical forms have been studied with the direct immunofluorescence technique. Core antigen was present in 11 patients, delta antigen in 4 patients: both antigens in 3 cases. The percent rate of positive nuclei varied from 5 to 80%. All subjects negative for both antigens showed a favourable course. Delta antigen seems to be associated to forms with unsatisfactory course notwithstanding therapy, particularly to relapses and recurrences of chronic hepatitis in such a way as to hypothesize the possible responsibility either of another hepatitic virus (non A, non B virus) or of a different virus. Core morphological expression frequent in chronic hepatitis submitted to immunodepressive treatment, corresponded approximately to the finding thus far reported for the adults. The interpretation of these results, though difficult, shows remarkable interest for the pathogenetic and therapeutic considerations which follow.