The responses to TSH of tissue cAMP levels in thyroid slices from patients with Graves' disease were significantly lower than those in normal thyroid slices. Conversely, tissue cAMP levels in thyroid slices from these patients were greatly increased by beta-adrenergic agonists, either isoproterenol or norepinephrine compared with those in normal thyroid slices. The elevation of cAMP levels induced by TSH in normal thyroid slices was significantly reduced by norepinephrine via alpha-adrenergic action as reported previously in canine thyroid slices, while such an elevation by TSH of cAMP levels in slices of Graves' disease thyroids was not inhibited, or rather increased by norepinephrine. These results indicate that, in addition to low responses to TSH, alpha- and beta-adrenergic systems were functionally altered in thyroid tissues of patients with Graves' disease.