Primary squamous cell carcinoma (SCC) of the thyroid gland is a rare diagnosis, since there is no squamous epithelium in the thyroid gland. SCC of the thyroid is highly aggressive with a poor prognosis. We present a case of primary SCC of the thyroid: this 88-year-old male patient had a history of hyperthyroidism which was treated with radioactive iodine 25 years earlier. Whether this treatment could be related to SCC of the thyroid is not clear. We treated our patient with thyroidectomy and subsequent intensified radiotherapy. Six months after treatment our patient is doing well and there is no sign of local reoccurrence. Our work-up is described, including the differentiation from metastatic disease. The origin of squamous cell carcinoma in the thyroid is uncertain; we discuss some theoretical considerations. We conclude that after excluding metastatic disease, thyroidectomy combined with radiotherapy is the treatment of choice.