SummaryThe difference between the«toxic adenoma»and the classic hyperthyroidism may be based on a less pronounced symptomatology and the absence of exophtalmos. The autonomous character of the toxic adenoma can be confirmed merely by routine scanning followed by two dynamic tests, the suppression test, using tri-iodothyronin, and the stimulation test using thyreostimulin : moreover these tests allow to differentiate between the adenoma and the other forms of nodular hyperplasia. The treatment of choice is the surgical excision limited to the toxic nodule. If contraindications exist or if the patient declines this treatment, the adenoma can be eliminated by a therapeutic dose of iodine131I. The authors treated 21 cases with a single dose of 6 to 4omC corresponding to a mean energy of 25,000 rad deposited within the nodule. The signs of toxicosis disappeared in all patients, although the adenoma treated in this manner could maintain his function or not.