Findings in our series of patients and a review of the literature seem to suggest that metastatic cancer to the thyroid is much more common that is clinically evident. The clinical presentation of an asymptomatic mass, normal thyroid functions, and a cold nodule on thyroid scan can occur months to years after treatment of a primary cancer and thus often produces a clinical dilemma. Workup should include ruling out other metastatic cancer and fine-needle aspiration of the thyroid mass. If isolated metastatic cancer to the thyroid is found, surgical resection should be performed, usually by lobectomy and isthmusectomy. Unfortunately, the prognosis is poor, but surgery often prolongs the disease-free interval and occasionally will be curative.