Urine samples of patients with Graves′ and Hashimoto′s diseases were dialysed and subjected to a sensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) for anti-thyroglobulin IgG. Anti-thyroglobulin IgG in urine was reacted simultaneously with 2,4-dinitrophenylated thyroglobulin and thyroglobulin-β-D-galactosidase conjugate. The immune complex formed consisting of the three components was trapped onto polystyrene balls coated with (anti-2,4-dinitrophenyl group) IgG, eluted with ϵN-2,4-dinitrophenyl-L-lysine and transferred onto polystyrene balls coated with (anti-human IgG γ-chain) IgG. β-D-Galactosidase activity bound to the last polystyrene balls was assayed by fluorometry. Anti-thyroglobulin IgG was detected in most of the patients. The detection of anti-thyroglobulin IgG in urine by the immune complex transfer enzyme immunoassay was suggested to be useful as a diagnostic aid for autoimmune thyroid diseases.