An analysis was made of 75 pregnant patients who received medicamentous therapy for Graves' disease before the investigated pregnancy and 20 healthy pregnant women with normal pregnancies and term delivery. A severe form of hyperthyreosis was found in 35 examined persons. A separate analysis was made of the patients who had no previous therapy (17) and pregnant patients who were treated with antithyroid drugs (18), with the aim to investigate their effect on the course and outcome of pregnancy and the condition of the newborn infant. In all examined pregnant women the median values with standard deviations for TSH, T4 and T3 in each trimester of pregnancy, the dynamics of their trends, as well as the correlation of values in treated and untreated pregnant women were recorded. The analysis of the pregnancy course in patients with hyperthyreosis indicated a significantly higher incidence of gestational diabetes and EPH gestoses (p less than 0.001). A separate analysis indicated that hyperthyreoidism is one of the risk factors in the occurrence of gestational diabetes. There were 90% of pregnant women who were delivered in an euthyroid condition achieved before pregnancy and maintained during pregnancy, 85% with mild and 77.1% with severe hyperthyreosis. The comparison of treated and untreated patients indicated that the percentage of delivered patients is similar (77.8:76.4), while the incidence of spontaneous abortions was higher (16.7:11.8) and of fetal deaths lower (5.5:11.8). There was one stillbirth in an untreated patient, while the remaining infants were healthy. The authors are of the opinion that it is necessary to achieve remission before pregnancy. In patients with severe hyperthyreosis the authors suggest the administration of antithyreoid drugs.