Medullary thyroid carcinoma (MTC) is rare derived from C cells of the thyroid gland and represents approximately 5% of all thyroid carcinomas. We report a case of a 74 years old male with MTC, diagnosed in 2002 and treated with total thyroidectomy and lymphadenectomy. A metastatic lesion was diagnosed on the right ventricle by indium-111-octreoscan, fluorine-18-fluorodeoxyglucose-positron emission tomography/computerized tomography, echocardiography, magnetic resonance imaging, high resolution computed tomography and was confirmed by histopathology. We present the results of treatment of this patient with yttrium-90-DOTA-tyr(3)-octreotide.