Twenty-five cases of thyrotoxicosis were compared to twenty-five controls. The incidence of 'neuroticism' in the thyrotoxic group was significantly higher than in the control group. 'Personality defenses rendered these patients vulnerable to thyrotoxicosis. However, no specificity can be claimed.' The thyrotoxicosis is a form of maladaptation, but no real information is available to explain why the thyroid is affected. Disease of the thyroid may be a symbolic expression of fantasies of oral impregnation, a symbolic expression of introjection of an ambivalently regarded mother or mother's breast, or a nonspecific affective concomitant of regressively released anxiety. In some cases the thyrotoxicosis appeared to be the equivalent of a depressive reaction. The findings in this series of thyrotoxic patients differ in many ways from other reported series, an indication that we must be wary of conclusions drawn from small groups of patients.