In this paper we studied the presence of HBsAg and immunoglobulin G on the liver cell surface in patients with chronic HBV infection. For this purpose we developed a double immunofluorescence technique which allowed the contemporary detection of membrane antigens and the intracellular expression of HBV antigens (HbsAg and HBcAg) within the same hepatocyte. In 16 selected patients (10 with CAH and 6 with normal liver or NSRH) we found that the presence of membranous HBsAg is associated to the healthy carrier state of the infection and it correlates with the presence of abundant HBsAg in the cytoplasm of liver cells. On the contrary, membrane-bound IgG was found in patients with active virus replication and its presence correlates with nuclear HBcAg. On the basis of these results a modulatory effect of the cytophilic IgG on HBV cellular expression is proposed.