Out of a group of 361 patients with various anatomo-clinical forms of hyperthyroidia--of which 328 had underwent surgery--hospitalized in the Surgical Clinic from Jassy between 1965 and 1974, a total of 17 observations are analised, from the clinical and the therapeutical viewpoint, that showed postoperative thyreotoxicosis crisis. The fact is stressed that the prophylaxis of the crisis is dominated by the principle that no case of hyperthyroidia should be operated on before it has been perfectly balanced from the endocrinological viewpoint. The complex treatment of the cases that are presented included a symptomatic component to which were associated oxygen therapy, tonics, vitamins, hepatotrop preparations, eventually antibiotics. The results obtained--complete recovery in all the cases--can be compared with the best from the literature.