In patients with the first manifestation of hyperthyroidism of Graves' disease, antithyroid drug treatment is the therapy of first choice. Treatment has to be carried out depending on iodine supply of the individual patient with the lowest possible drug dose. Controls of treatment have to be done in short intervals (every 2 weeks) until euthyroidism is reached, afterwards controls of thyroid function have to be done every three months. After euthyroidism is established, the combination of antithyroid drug therapy with thyroid hormones may be useful to avoid hypothyroidism or goiter development during treatment in contrast to a monotherapy with antithyroid drugs. Antithyroid drug treatment has to be carried out for one year. The remission rate of patients does not increase with higher doses of antithyroid drugs or a longer treatment duration. The determination of TSH receptor antibodies does not help predicting a relapse of hyperthyroidism of Graves' disease in the individual patient at the end of treatment. Regular follow-up controls after antithyroid drug treatment are necessary to recognize relapse of Graves' disease in time.