Circulating immune complexes containing IgG, IgM and HBsAg in sera from groups of patients with various liver diseases were detected by the Clq and conglutinin solid phase assays. Elevated levels of antigen-non-specific complexes were observed in sera from all groups and complexes containing IgG were present to a greater extent than were IgM-containing complexes. However, only sera from HBsAg-positive patients had significant levels of complexes containing HBsAg.