The material presented was secured from the first 15 hyperthyroid patients seen consecutively in the medical wards of a large hospital. Typical case histories showing the emotional involvements of the patients are presented. It was found that emotional difficulties regularly preceded the onset of thyroidtoxicosis, and that the personality structures of the patients were markedly similar. There was likewise a striking similarity of the emotional traumata initiating the thyroid imbalances. It is concluded that emotional factors play an important role in the onset and development of this glandular dysfunction.