Intracardiac ectopic thyroid tissue is a rare lesion. We present a case of successful excision of an ectopic thyroid adenoma originated from the right ventricular aspect of the interventricular septum and extending to the right ventricular outflow tract. The 12-month follow-up shows normal thyroid function and good clinical status of the patient. In our estimation, there was no case with an intracardiac ectopic thyroid adenoma reported before in China.