An enzyme-linked immunosorbent assay based on the ability of polyethylene-glycol (PEG) fixed on a solid support to adsorb circulating macromolecules (PEG-solid phase test) was developed in order to provide evidence for the existence of immune complexes of HBeAg/anti-HBe (HBeAg/anti-HBe complex) in sera of HBsAg chronic carriers. The method can detect HBeAg in immune complexes whether antigen or antibody is in excess. In the chronic phase of HBV infection, HBeAg/anti-HBe complexes are formed transiently in the course of the disease, unrelated to the phases of virus replication or peaks of hepatocytolysis, or to the histologic picture of liver disease. Our study indicates that this method offers a new approach to the understanding of biological and clinical problems of the HBeAg/anti-HBe antigenic system in chronic HBV infection.