The direct and indirect immunofluorescence technique has been used to study liver biopsies in children affected by different forms of chronic HBsAg positive Hepatitis. The method allows to study the long run changes of the antigens correlated to HBV and of the related immunological phenomena both in serum (autoantibodies) and in the tissue (immunoglobulins and immunocomplexes in the liver). The results obtained are satisfactory.