Three hundred and thirty Graves' disease patients (258 F. 72 M. ; mean age = 50 +/- 07 years) were treated by 131I from 1961 to 1979 ; 57 % had a goiter and 32 % had exophthalmos. One or several doses of radioiodine were given to each patient without dosimetry. The mean total dose (+/- SEM) was = 8,51 +/- 0,44 mCi and the mean for the first dose 4,34 +/- 4 ans 54,8 % of the patients received only one dose but 10,3 % of them had more than 3 doses. Data obtained by actuarial methods showed 66 % of the cases to be in remission in less than 2 years ; the frequency of hypothyroidism increased steadily by 3 % every year to give 15 % at 5 years and 30 % at 10 years. Remission was slower to occur in goitrous subjects and hypothyroidism was less frequent in this group despite doses significantly higher of radioiodine (p less than 0,001). Recovery was also slower among exophthalmos patients. Finally, the mean 3-hour radioiodine uptake and plasma T3 level were significantly lower six months after the first therapeutic dose among those who were cured of thier hyperthyroidism within two years.