A similarity between exophthalmic goiter and leukemia, especially as regards the ratio of the basal metabolic rate to the basal pulse rate, has been pointed out by Minot and Means.1 Friedgood2 reported that a response to compound solution of iodine similar to that seen in patients with exophthalmic goiter was obtained in six of ten patients with lymphatic leukemia. Both of these communications contain further comment on the similarities of the two conditions. Recently Dameshek, Berlin and Blumgart3 have reported a case of chronic lymphatic leukemia (aleukemic) in which total ablation of the thyroid gland resulted in considerable clinical and hematologic improvement. We have been more interested in the fundamental differences between exophthalmic goiter and leukemia than in their similarities. We have reported investigations4 which show that protein catabolism is an important factor in the production of hypermetabolism in the common blood dyscrasias. One difference between