Primary squamous cell carcinoma of the thyroid gland is a rare disease which comprises only 1% of all the malignant tumors of the thyroid gland. Although the histogenic origin of squamous cell carcinoma of the thyroid gland has been debated, squamous metaplasia of the follicular cells is the most widely accepted histogenic theory for this neoplasm, although in rare exception, it can originate from a remmant of the thyroglossal duct or ultimobranchial body. Squamous cell carcainoma of the thyroid can occur in a pure form or mixed with adenocarcinoma. Because their clinical behavior is more aggressive than that of differentiated papillary or follicullar carcinoma of the thyroid gland, the tumor is treated more vigorously at its initial stage. Radical surgical resection is usually done for cure. The lesions are usually radioresistant, and chemotherapy has not been shown to alter the course of the disease. Recently authors experienced one case of primary squamous cell carcinoma of the thyroid gland at Yonsei University College of Medicine, we report our case with a brief review of literature.