We have reviewed the immunology of thyroid autoimmunity with special reference to the importance of B lymphocytes (B cells) in thyroidal and extrathyroidal Graves' disease (GD), thus providing a framework for the hypothesis that B cell depletion may be beneficial in GD. Additionally, after reviewing the efficacy and safety in other autoimmune diseases, we propose that treatment with the B cell-depleting agent Rituximab may become a clinically relevant treatment option in selected cases of GD, particularly when complicated with thyroid-associated ophthalmopathy.