Two rabbits (RG-1, RG-2) were immunized with rabbit thyroglobulin (RTg) purified from thyroid glands of four other normal rabbits of the same strain, and bled serially. Antisera were obtained at different times after the first immunization and kept separately and studied. Production of anti-RTg as well as anti-thyroid hormone antibodies such as anti-thyroxine (T4) and anti-triiodothyronine (T3) antibodies was observed in both rabbits. Physicochemical parameters of anti-RTg antibodies with RTg, T4, and T3 were calculated in two selected antisera (70-day and 253-day) of each of the rabbits, using a Scatchard plot. Extraction of serial sera from both rabbits disclosed the presence of larger amounts of T3 and T4 in immune sera than in preimmune serum. Examination of pathology of thyroid glands and kidneys in both rabbits was negative for the lesions of autoimmune thyroiditis and immune nephritis. These results indicate that anti-Tg as well as anti-thyroid hormone autoantibodies can be raised without thyroid pathology in rabbit by immunization with autologous Tg.