Primary squamous cell carcinoma of the thyroid gland is a very rare event, representing much less than 1% of all malignant tumors of the thyroid gland. The cancer is characterized by rapidly progressive clinical course in spite of its differentiated morphologic features. In most cases, a squamous epithelium is believed to be a result of metaplasia of a follicular epithelium, although in rare exceptions, it can originate from a remnant of the thyroglossal duct or ultimobranchial body. Squamous cell carcinoma of the thyroid gland can occur in a pure form or mixed with adenocarcinoma. Because their clinical behavior is more aggressive than that of other malignant neoplasm of thyroid gland, the tumor should be treated more vigorously at its initial stage. Recently, authors experienced one case of primary squamous cell carcinoma of the thyroid gland. We report our case with a brief review of literature.