Intracardiac thyroid goiter (struma cordis) is an exceptionally rare finding. To our knowledge, only two cases have been reported in the literature to date. A middle-aged woman was the subject of our case, in which an intracardiac tumor was clinically diagnosed and surgically resected. The mass, adhesive to the ventricular septum and obstructing the right ventricular outlow tract, histologically was formed by thyroid tissue, separated from the myocardium by fibrous tissue. The woman died of renal failure two weeks after the operation, and at autopsy the thyroid gland showed strumous changes. The similarity to previously reported cases suggests a dysembryologic origin of this ectopia.