SUMMARYE‐rosettes (T‐lymphocytes) have been demonstrated to be increased in the peripheral blood of patients with untreated Graves’disease and decreased when these patients go into remission induced by antithyroid drugs. In patients similarly treated but not in remission, a high percentage of E‐rosettes persisted. The degree of suppression by T3of the thyroidal131I uptake correlated well with the percentage of E‐rosettes. We suggest that E‐rosette counts may prove to be a useful test for detecting remissions in thyrotoxic patients treated with antith