We report two cases of hyperthyroidism clinically associated to edema, in which no usual causes for the latter were found. Correction of the hyperthyroidism state was associated with complete resolution of edema. The fact that one of the cases consisted of a farmacologically induced hyperthyroidism points to a direct effect of the thyroid hormone itself as the origin of this complication. The de novo occurrence of edema can be due to thyroid hyperfunction as the only underlying cause, the presence of other associated factors such as heart failure, hypoproteinemia or dermopathy not being necessary for its development.