Metastases to the thyroid gland are rarely encountered in clinical practice. They may originate from various primary sites, mainly kidney, lung, breast, esophagus and uterus. Prostate cancer is one of the most frequent malignancies in men. It generally has a favorable course, and autopsy series have shown occult prostate cancer in many subjects, especially in aged males. However, prostate cancer sometimes exhibits an aggressive behavior and cases with a poor prognosis have been reported. Occasional reports of metastasis from prostate cancer to the thyroid gland have been documented. We describe the case of a 73-year-old patient presenting with thyroid metastasis from long-standing prostate cancer.