The formation and clearance of circulating IgA immune complexes from blood to bile was investigated in this study. The i.v. injection of either MOPC-315, an IgA M-component with anti-dinitrophenyl (DNP) specificity, or TEPC-15, an IgA M-component of a different specificity, was followed by i.v. injection of 125I-DNP10-bovine serum albumin (BSA) as the antigen. The formation and clearance of IgA immune complexes in the circulation of MOPC-315-treated, but not TEPC-15-treated animals was deømonstrated by immunoprecipitation with polyacrylamide beads coated with rabbit anti-mouse IgA. IgA-125I-DNP10-BSA complexes were identified in the bile from MOPC-315-treated, but not TEPC-15-treated animals utilizing this same immunoprecipitation technique. These observations suggest that the liver or bile ducts transport IgA immune complexes from blood into bile. The clearance of 125I-DNP10-BSA from the circulation was documented by coprecipitation with rabbit anti-BSA and BSA. The clearance of this circulating antigen was slower in the MOPC-315-treated than in the TEPC-15-treated animals suggesting that under the conditions of the present experiment, circulating antigen is cleared more slowly after IgA immune complex formation.