We report herein the case of a 67-year-old man who was admitted to our hospital with a 3-month history of hoarseness, a cervical mass, and weak muscles of the extremities 6 years after undergoing a right colectomy for carcinoma. Physical and imaging examinations disclosed a nodule in the thyroid with swollen cervical lymph nodes, multiple pulmonary lesions with pleural effusion, and a cerebral mass. Fine-needle aspiration cytology of the thyroid nodule and brush cytology of the lung mass revealed adenocarcinoma, which was consistent with a diagnosis of metastases from the primary colon adenocarcinoma to the thyroid, brain, and lung. The patient eventually died from the malignancy, although he survived for 4 months after the disclosure of the metastases. The rarity, diagnosis, and prognosis of thyroid metastasis from colon carcinoma are discussed.