Thyrotoxic crisis (thyroi storm) is a rare complication of hyperthyroidism. It can be observed not only in thyroid autonomy with latent hyperfunction after exposure to iodine, but also in Graves' disease with overt hyperfunction. Adequate management of thyrotoxic crisis is still controversial. We report about four patients (four women, mean age 75 years) with Graves' disease who developed thyrotoxic crisis during therapy with antithyroid drugs so that surgical intervention became necessary. The patients had been admitted to the hospital for nonspecific symptoms such as headache, cachexy, and psychosis. Thyroid hormone levels had reached twice the normal range prior to surgery. All patients showed severe neurological deficits leading to coma. In three cases euthyroidism was achieved within two days after surgery. The neurological symptoms disappeared after an average of four days. The postoperative course did not show severe complications and all patients recovered completely. Especially in the elderly a monosymptomatic or nonspecific course of thyroid storm with neurological symptoms may represent a severe and life-threatening situation. In these cases surgery can become necessary even if euthyroidism has not been achieved preoperatively.